Computer Science & Mathematics
http://www.mdpi.com/journal/computer-math
Latest open access articles published in Computer Science & Mathematics at http://www.mdpi.com/journal/computer-math<![CDATA[JSAN, Vol. 5, Pages 3: Social Internet of Vehicles for Smart Cities]]>
http://www.mdpi.com/2224-2708/5/1/3
Digital devices are becoming increasingly ubiquitous and interconnected. Their evolution to intelligent parts of a digital ecosystem creates novel applications with so far unresolved security issues. A particular example is a vehicle. As vehicles evolve from simple means of transportation to smart entities with new sensing and communication capabilities, they become active members of a smart city. The Internet of Vehicles (IoV) consists of vehicles that communicate with each other and with public networks through V2V (vehicle-to-vehicle), V2I (vehicle-to-infrastructure) and V2P (vehicle-to-pedestrian) interactions, which enables both the collection and the real-time sharing of critical information about the condition on the road network. The Social Internet of Things (SIoT) introduces social relationships among objects, creating a social network where the participants are not humans, but intelligent objects. In this article, we explore the concept of the Social Internet of Vehicles (SIoV), a network that enables social interactions both among vehicles and among drivers. We discuss technologies and components of the SIoV, possible applications and issues of security, privacy and trust that are likely to arise.Journal of Sensor and Actuator Networks2016-02-0651Review10.3390/jsan501000332224-27082016-02-06doi: 10.3390/jsan5010003Leandros MaglarasAli Al-BayattiYing HeIsabel WagnerHelge Janicke<![CDATA[Algorithms, Vol. 9, Pages 15: A Geometric Orthogonal Projection Strategy for Computing the Minimum Distance Between a Point and a Spatial Parametric Curve]]>
http://www.mdpi.com/1999-4893/9/1/15
A new orthogonal projection method for computing the minimum distance between a point and a spatial parametric curve is presented. It consists of a geometric iteration which converges faster than the existing Newton’s method, and it is insensitive to the choice of initial values. We prove that projecting a point onto a spatial parametric curve under the method is globally second-order convergence.Algorithms2016-02-0691Article10.3390/a9010015151999-48932016-02-06doi: 10.3390/a9010015Xiaowu LiZhinan WuLinke HouLin WangChunguang YueQiao Xin<![CDATA[IJGI, Vol. 5, Pages 12: Assessing the Distribution of Urban Green Spaces and its Anisotropic Cooling Distance on Urban Heat Island Pattern in Baotou, China]]>
http://www.mdpi.com/2220-9964/5/2/12
An essential part of urban natural systems, urban green spaces play a crucial role in mitigating the urban heat island effect (UHI). The UHI effect refers to the phenomenon where the temperature within a city is higher than that of the surrounding rural areas. The effects of the spatial composition and configuration of urban green spaces on urban land surface temperature (LST) have recently been documented. However, few studies have examined the effects of the directionality and distribution of green spaces on LST. In this study, we used a landscape index to describe the change in pattern of heat island intensity for the city of Baotou, China. We then used a semi-variable function and nearest neighbor algorithm to analyze the cooling effects of green spaces. We found that: (1) the cooling distance of an urban green space was not only influenced by its size, vegetation cover, and shape, but also showed anisotropy. In general, the larger the area of the urban green space and the higher the value of Normalized Difference Vegetation Index (NDVI; a measure of plant photosynthetic activity), the larger the cooling distance within a certain threshold. Green spaces with more regular shapes displayed higher LST mitigation; however, the cooling distance was directional, and cooling effects depended on the semi-major axis and semi-minor axis of the green space. (2) The distribution of the urban green space within the landscape played a key role in mitigating the UHI effect. Within a certain area, the cooling effect of green spaces that are evenly distributed was greater than that which was associated with either green spaces that were large in area or where greens spaces were aggregated in the landscape. Therefore, within urban areas, where space is limited, urban planning should account for green spaces that are relatively scattered and evenly distributed to maximize cooling effects. The results of this study have key implications for sustainable urban planning and development; to mitigate urban heat island effects it is important to not only increase canopy cover or the size of urban green spaces, but also to optimize their spatial configuration.ISPRS International Journal of Geo-Information2016-02-0652Article10.3390/ijgi5020012122220-99642016-02-06doi: 10.3390/ijgi5020012Tongliga BaoXueming LiJing ZhangYingjia ZhangShenzhen Tian<![CDATA[Computation, Vol. 4, Pages 8: CFD Simulation and Experimental Analyses of a Copper Wire Woven Heat Exchanger Design to Improve Heat Transfer and Reduce the Size of Adsorption Beds]]>
http://www.mdpi.com/2079-3197/4/1/8
The chief objective of this study is the proposal design and CFD simulation of a new compacted copper wire woven fin heat exchanger and silica gel adsorbent bed used as part of an adsorption refrigeration system. This type of heat exchanger design has a large surface area because of the wire woven fin design. It is estimated that this will help improve the coefficient of performance (COP) of the adsorption phase and increase the heat transfer in this system arrangement. To study the heat transfer between the fins and porous adsorbent reactor bed, two experiments were carried out and matched to computational fluid dynamics (CFD) results.Computation2016-02-0641Review10.3390/computation401000882079-31972016-02-06doi: 10.3390/computation4010008John White<![CDATA[Computation, Vol. 4, Pages 7: Applications of Computational Modelling and Simulation of Porous Medium in Tissue Engineering]]>
http://www.mdpi.com/2079-3197/4/1/7
In tissue engineering, porous biodegradable scaffolds are used as templates for regenerating required tissues. With the advances in computational tools, many modeling approaches have been considered. For example, fluid flow through porous medium can be modeled using the Brinkman equation where permeability of the porous medium has to be defined. In this review, we summarize various models recently reported for defining permeability and non-invasive pressure drop monitoring as a tool to validate dynamic changes in permeability. We also summarize some models used for scaffold degradation and integrating mass transport in the simulation.Computation2016-02-0641Article10.3390/computation401000772079-31972016-02-06doi: 10.3390/computation4010007Carrie GermanSundararajan Madihally<![CDATA[IJGI, Vol. 5, Pages 15: Detection of Land Use/Land Cover Changes and Urban Sprawl in Al-Khobar, Saudi Arabia: An Analysis of Multi-Temporal Remote Sensing Data]]>
http://www.mdpi.com/2220-9964/5/2/15
While several studies examined land use and land cover changes in the central and western parts of Saudi Arabia, this study is the first to use remote sensing data to examine the decadal land cover changes in Saudi Arabia’s eastern coastal city of Al-Khobar between 1990 and 2013. Specifically, it utilized ISODATA classification method to classify Landsat TM, ETM+, and OLI data collected from 1990, 2001, and 2013 and then detected changes in the land cover within the study area. It then measured urban sprawl by calculating the relative Shannon’s entropy index values for the three years. With overall classification accuracies greater than 85%, the results show that urban built-up areas increased by 117% between 1990 and 2001 and 43.51% from 2001 to 2013. Vegetation increased by 110% from 1990 to 2001 and by 52% between 2001 and 2013. The entropy index values of 0.700 (1990), 0.779 (2001), and 0.840 (2013) indicates a high rate of urban sprawl and the city dispersing near the outskirts and towards the neighboring cities of Dhahran and Dammam. Future studies should examine the current challenges faced by the city’s residents due to urban expansion and attempt to find ways to resolve them in the near future.ISPRS International Journal of Geo-Information2016-02-0652Article10.3390/ijgi5020015152220-99642016-02-06doi: 10.3390/ijgi5020015Muhammad Rahman<![CDATA[Computation, Vol. 4, Pages 10: Localized Polycentric Orbital Basis Set for Quantum Monte Carlo Calculations Derived from the Decomposition of Kohn-Sham Optimized Orbitals]]>
http://www.mdpi.com/2079-3197/4/1/10
In this work, we present a simple decomposition scheme of the Kohn-Sham optimized orbitals which is able to provide a reduced basis set, made of localized polycentric orbitals, specifically designed for Quantum Monte Carlo. The decomposition follows a standard Density functional theory (DFT) calculation and is based on atomic connectivity and shell structure. The new orbitals are used to construct a compact correlated wave function of the Slater–Jastrow form which is optimized at the Variational Monte Carlo level and then used as the trial wave function for a final Diffusion Monte Carlo accurate energy calculation. We are able, in this way, to capture the basic information on the real system brought by the Kohn-Sham orbitals and use it for the calculation of the ground state energy within a strictly variational method. Here, we show test calculations performed on some small selected systems to assess the validity of the proposed approach in a molecular fragmentation, in the calculation of a barrier height of a chemical reaction and in the determination of intermolecular potentials. The final Diffusion Monte Carlo energies are in very good agreement with the best literature data within chemical accuracy.Computation2016-02-0641Article10.3390/computation4010010102079-31972016-02-06doi: 10.3390/computation4010010Claudio AmovilliFranca FlorisAndrea Grisafi<![CDATA[IJGI, Vol. 5, Pages 14: A Generic Model to Exploit Urban Regulation Knowledge]]>
http://www.mdpi.com/2220-9964/5/2/14
The Right to Build is defined by textual elements that determine what an owner can build on a parcel. Such regulations contain elements that can influence the development of territories. Expressed through legal texts, their effects on the territory are difficult to assess because of the documents’ complexity and of the diversity of urban configurations. In this paper, we present a generic and extendable model to represent such regulations. This model is based on (1) a representation of geographical concepts (attributes, features and relations) mentioned in regulations and (2) rules formalized with Object Constraints Language (OCL). We also propose an implementation that allows the handling of formalized rules in order to check if a building configuration proposal respects urban regulations. Many applications are possible in order to assist in the conception of such regulations, land acquisition strategy or territorial evolution studies, in this article, we notably describe a future application dedicated to assist building permit surveyors.ISPRS International Journal of Geo-Information2016-02-0652Article10.3390/ijgi5020014142220-99642016-02-06doi: 10.3390/ijgi5020014Mickaël BrasebinJulien PerretSébastien MustièreChristiane Weber<![CDATA[IJGI, Vol. 5, Pages 13: A Hybrid Method for Interpolating Missing Data in Heterogeneous Spatio-Temporal Datasets]]>
http://www.mdpi.com/2220-9964/5/2/13
Space-time interpolation is widely used to estimate missing or unobserved values in a dataset integrating both spatial and temporal records. Although space-time interpolation plays a key role in space-time modeling, existing methods were mainly developed for space-time processes that exhibit stationarity in space and time. It is still challenging to model heterogeneity of space-time data in the interpolation model. To overcome this limitation, in this study, a novel space-time interpolation method considering both spatial and temporal heterogeneity is developed for estimating missing data in space-time datasets. The interpolation operation is first implemented in spatial and temporal dimensions. Heterogeneous covariance functions are constructed to obtain the best linear unbiased estimates in spatial and temporal dimensions. Spatial and temporal correlations are then considered to combine the interpolation results in spatial and temporal dimensions to estimate the missing data. The proposed method is tested on annual average temperature and precipitation data in China (1984–2009). Experimental results show that, for these datasets, the proposed method outperforms three state-of-the-art methods—e.g., spatio-temporal kriging, spatio-temporal inverse distance weighting, and point estimation model of biased hospitals-based area disease estimation methods.ISPRS International Journal of Geo-Information2016-02-0652Article10.3390/ijgi5020013132220-99642016-02-06doi: 10.3390/ijgi5020013Min DengZide FanQiliang LiuJianya Gong<![CDATA[Systems, Vol. 4, Pages 12: Accounting Treatment for Carbon Emission Rights]]>
http://www.mdpi.com/2079-8954/4/1/12
In light of the growing demand for sustainable behavior and the special interest that has emerged regarding the social and environmental impact of firms, the purpose of this research is to analyze the determinants of the accounting treatment of emission rights. To achieve that purpose, we use a sample composed of 119 firms worldwide from different countries and activity sectors for the period 2011. Our findings show different accounting treatments depending on a series of factors. Specifically, firms pertaining to countries that have adopted Environmental Trading Schemes (ETS) tend to account for emission rights through provisions, investments, or as inventory. For their part, firms that issue indicators that appear in the report drawn up by KPMG and GRI (2007) tend to account for these entries as expenses, especially as R + D expenses. Finally, firms located in countries that signed the Kyoto protocol have a tendency to not account for carbon emission rights. The findings of this work can be considered of great interest on the international level because our research contributes to the scant previous literature regarding the accounting treatment of emission rights.Systems2016-02-0641Article10.3390/systems4010012122079-89542016-02-06doi: 10.3390/systems4010012Isabel Gallego-AlvarezJennifer Martínez-FerreroBeatriz Cuadrado-Ballesteros<![CDATA[Axioms, Vol. 5, Pages 6: Entropy Production Rate of a One-Dimensional Alpha-Fractional Diffusion Process]]>
http://www.mdpi.com/2075-1680/5/1/6
In this paper, the one-dimensional α-fractional diffusion equation is revisited. This equation is a particular case of the time- and space-fractional diffusion equation with the quotient of the orders of the time- and space-fractional derivatives equal to one-half. First, some integral representations of its fundamental solution including the Mellin-Barnes integral representation are derived. Then a series representation and asymptotics of the fundamental solution are discussed. The fundamental solution is interpreted as a probability density function and its entropy in the Shannon sense is calculated. The entropy production rate of the stochastic process governed by the α-fractional diffusion equation is shown to be equal to one of the conventional diffusion equation.Axioms2016-02-0551Article10.3390/axioms501000662075-16802016-02-05doi: 10.3390/axioms5010006Yuri Luchko<![CDATA[Computation, Vol. 4, Pages 6: Computation of the Likelihood of Joint Site Frequency Spectra Using Orthogonal Polynomials]]>
http://www.mdpi.com/2079-3197/4/1/6
In population genetics, information about evolutionary forces, e.g., mutation, selection and genetic drift, is often inferred from DNA sequence information. Generally, DNA consists of two long strands of nucleotides or sites that pair via the complementary bases cytosine and guanine (C and G), on the one hand, and adenine and thymine (A and T), on the other. With whole genome sequencing, most genomic information stored in the DNA has become available for multiple individuals of one or more populations, at least in humans and model species, such as fruit flies of the genus Drosophila. In a genome-wide sample of L sites for M (haploid) individuals, the state of each site may be made binary, by binning the complementary bases, e.g., C with G to C/G, and contrasting C/G to A/T, to obtain a “site frequency spectrum” (SFS). Two such samples of either a single population from different time-points or two related populations from a single time-point are called joint site frequency spectra (joint SFS). While mathematical models describing the interplay of mutation, drift and selection have been available for more than 80 years, calculation of exact likelihoods from joint SFS is difficult. Sufficient statistics for inference of, e.g., mutation or selection parameters that would make use of all the information in the genomic data are rarely available. Hence, often suites of crude summary statistics are combined in simulation-based computational approaches. In this article, we use a bi-allelic boundary-mutation and drift population genetic model to compute the transition probabilities of joint SFS using orthogonal polynomials. This allows inference of population genetic parameters, such as the mutation rate (scaled by the population size) and the time separating the two samples. We apply this inference method to a population dataset of neutrally-evolving short intronic sites from six DNA sequences of the fruit fly Drosophila melanogaster and the reference sequence of the related species Drosophila sechellia.Computation2016-02-0441Article10.3390/computation401000662079-31972016-02-04doi: 10.3390/computation4010006Claus VoglJuraj Bergman<![CDATA[Econometrics, Vol. 4, Pages 7: Multiple Discrete Endogenous Variables in Weakly-Separable Triangular Models]]>
http://www.mdpi.com/2225-1146/4/1/7
We consider a model in which an outcome depends on two discrete treatment variables, where one treatment is given before the other. We formulate a three-equation triangular system with weak separability conditions. Without assuming assignment is random, we establish the identification of an average structural function using two-step matching. We also consider decomposing the effect of the first treatment into direct and indirect effects, which are shown to be identified by the proposed methodology. We allow for both of the treatment variables to be non-binary and do not appeal to an identification-at-infinity argument.Econometrics2016-02-0441Article10.3390/econometrics401000772225-11462016-02-04doi: 10.3390/econometrics4010007Sung JunJoris PinkseHaiqing XuNeşe Yıldız<![CDATA[Mathematics, Vol. 4, Pages 6: Microtubules Nonlinear Models Dynamics Investigations through the exp(−Φ(ξ))-Expansion Method Implementation]]>
http://www.mdpi.com/2227-7390/4/1/6
In this research article, we present exact solutions with parameters for two nonlinear model partial differential equations(PDEs) describing microtubules, by implementing the exp(−Φ(ξ))-Expansion Method. The considered models, describing highly nonlinear dynamics of microtubules, can be reduced to nonlinear ordinary differential equations. While the first PDE describes the longitudinal model of nonlinear dynamics of microtubules, the second one describes the nonlinear model of dynamics of radial dislocations in microtubules. The acquired solutions are then graphically presented, and their distinct properties are enumerated in respect to the corresponding dynamic behavior of the microtubules they model. Various patterns, including but not limited to regular, singular kink-like, as well as periodicity exhibiting ones, are detected. Being the method of choice herein, the exp(−Φ(ξ))-Expansion Method not disappointing in the least, is found and declared highly efficient.Mathematics2016-02-0441Article10.3390/math401000662227-73902016-02-04doi: 10.3390/math4010006Nur AlamFethi Belgacem<![CDATA[IJGI, Vol. 5, Pages 11: An Assessment of Urban Surface Energy Fluxes Using a Sub-Pixel Remote Sensing Analysis: A Case Study in Suzhou, China]]>
http://www.mdpi.com/2220-9964/5/2/11
Urban surface energy fluxes are closely associated with land-cover types (LCTs) and critical biophysical compositions. This study aims to assess the contribution of LCTs, vegetation fractional coverage (VFC) and percentage of impervious surface area (ISA%) to urban surface energy fluxes using remote sensing. An advanced urban surface energy flux algorithm was used to combine satellite imagery and meteorological station data to investigate the thermal environments in the city of Suzhou, China. The land cover abundances retrieved by multiple endmember spectral unmixing analysis (MESMA) were used to retrieve the per-pixel sensible heat flux (H) and latent heat flux (LE). The resultant heat fluxes were assessed using evaporation pan data collected from meteorological stations and ratios of the heat fluxes to the net radiation (Rn). Furthermore, spatial patterns of urban heat energy were investigated using an integrated analysis among land surface temperature (LST), heat fluxes, LCTs, VFC and ISA%. The high values of H and LST were found over the urbanized areas, which also had low values of LE. Conversely, the vegetated area was characterized with high LEs, as well as low LSTs and Hs. Moreover, a statistically-significant correlation (p &lt; 0.05; R2 = 0.88) was observed between LE and VFC at the zonal level, and a statistically-significant correlation (p &lt; 0.05; R2 = 0.90) was exhibited between H and ISA%. It is concluded that VFC, ISA% and LCTs are promising for delineating urban heat fluxes. Overall, this study indicates that remote sensing techniques can be used to quantify urban thermal environments.ISPRS International Journal of Geo-Information2016-02-0452Article10.3390/ijgi5020011112220-99642016-02-04doi: 10.3390/ijgi5020011Kai LiuJun-yong FangDong ZhaoXue LiuXiao-hong ZhangXiao WangXue-ke Li<![CDATA[Electronics, Vol. 5, Pages 8: FPGA Implementation of Blue Whale Calls Classifier Using High-Level Programming Tool]]>
http://www.mdpi.com/2079-9292/5/1/8
In this paper, we propose a hardware-based architecture for automatic blue whale calls classification based on short-time Fourier transform and multilayer perceptron neural network. The proposed architecture is implemented on field programmable gate array (FPGA) using Xilinx System Generator (XSG) and the Nexys-4 Artix-7 FPGA board. This high-level programming tool allows us to design, simulate and execute the compiled design in Matlab/Simulink environment quickly and easily. Intermediate signals obtained at various steps of the proposed system are presented for typical blue whale calls. Classification performances based on the fixed-point XSG/FPGA implementation are compared to those obtained by the floating-point Matlab simulation, using a representative database of the blue whale calls.Electronics2016-02-0451Article10.3390/electronics501000882079-92922016-02-04doi: 10.3390/electronics5010008Mohammed Bahoura<![CDATA[JSAN, Vol. 5, Pages 2: Enhanced Distributed Dynamic Skyline Query for Wireless Sensor Networks]]>
http://www.mdpi.com/2224-2708/5/1/2
Dynamic skyline query is one of the most popular and significant variants of skyline query in the field of multi-criteria decision-making. However, designing a distributed dynamic skyline query possesses greater challenge, especially for the distributed data centric storage within wireless sensor networks (WSNs). In this paper, a novel Enhanced Distributed Dynamic Skyline (EDDS) approach is proposed and implemented in Disk Based Data Centric Storage (DBDCS) architecture. DBDCS is an adaptation of magnetic disk storage platter consisting tracks and sectors. In DBDCS, the disc track and sector analogy is used to map data locations. A distance based indexing method is used for storing and querying multi-dimensional similar data. EDDS applies a threshold based hierarchical approach, which uses temporal correlation among sectors and sector segments to calculate a dynamic skyline. The efficiency and effectiveness of EDDS has been evaluated in terms of latency, energy consumption and accuracy through a simulation model developed in Castalia.Journal of Sensor and Actuator Networks2016-02-0351Article10.3390/jsan501000222224-27082016-02-03doi: 10.3390/jsan5010002Khandakar AhmedNazmus NafiMark Gregory<![CDATA[Risks, Vol. 4, Pages 2: Ruin Analysis of a Discrete-Time Dependent Sparre Andersen Model with External Financial Activities and Randomized Dividends]]>
http://www.mdpi.com/2227-9091/4/1/2
We consider a discrete-time dependent Sparre Andersen risk model which incorporates multiple threshold levels characterizing an insurer’s minimal capital requirement, dividend paying situations, and external financial activities. We focus on the development of a recursive computational procedure to calculate the finite-time ruin probabilities and expected total discounted dividends paid prior to ruin associated with this model. We investigate several numerical examples and make some observations concerning the impact our threshold levels have on the finite-time ruin probabilities and expected total discounted dividends paid prior to ruin.Risks2016-02-0341Article10.3390/risks401000222227-90912016-02-03doi: 10.3390/risks4010002Sung KimSteve Drekic<![CDATA[Econometrics, Vol. 4, Pages 6: Functional-Coefficient Spatial Durbin Models with Nonparametric Spatial Weights: An Application to Economic Growth]]>
http://www.mdpi.com/2225-1146/4/1/6
This paper considers a functional-coefficient spatial Durbin model with nonparametric spatial weights. Applying the series approximation method, we estimate the unknown functional coefficients and spatial weighting functions via a nonparametric two-stage least squares (or 2SLS) estimation method. To further improve estimation accuracy, we also construct a second-step estimator of the unknown functional coefficients by a local linear regression approach. Some Monte Carlo simulation results are reported to assess the finite sample performance of our proposed estimators. We then apply the proposed model to re-examine national economic growth by augmenting the conventional Solow economic growth convergence model with unknown spatial interactive structures of the national economy, as well as country-specific Solow parameters, where the spatial weighting functions and Solow parameters are allowed to be a function of geographical distance and the countries’ openness to trade, respectively.Econometrics2016-02-0341Article10.3390/econometrics401000662225-11462016-02-03doi: 10.3390/econometrics4010006Mustafa KorogluYiguo Sun<![CDATA[IJGI, Vol. 5, Pages 10: A Spatio-Temporal VGI Model Considering Trust-Related Information]]>
http://www.mdpi.com/2220-9964/5/2/10
Over the past several years, volunteered geographic information (VGI) has expanded rapidly. VGI collection has been proven to serve as a highly successful means of acquiring timely and detailed global spatial data. However, VGI includes several special properties. For example, the contributor’s reputation affects the quality of objects edited, and a geographic object may have multiple versions. The existing spatio-temporal data model cannot describe the unique properties of VGI. Therefore, a spatio-temporal VGI model considering trust-related information is presented in this paper. In this model, central elements of the VGI environment, e.g., geographic entity, entity state, state version, contributor, reputation, geographic event, and edit event, and their interaction mechanisms are analysed. Major VGI objects and relations are determined using the object-oriented method and trust-related operations, and their relationships are analysed, and nine linkage rules among trust-related operations are found to maintain the consistency of corresponding data. A prototype system for the spatio-temporal VGI model is presented, and the effectiveness of the model is verified.ISPRS International Journal of Geo-Information2016-02-0352Article10.3390/ijgi5020010102220-99642016-02-03doi: 10.3390/ijgi5020010Yijiang ZhaoXiaoguang ZhouGuangqiang LiHanfa Xing<![CDATA[Information, Vol. 7, Pages 3: Cross-Entropy-Based Energy-Efficient Radio Resource Management in HetNets with Coordinated Multiple Points]]>
http://www.mdpi.com/2078-2489/7/1/3
Energy efficiency and spectrum efficiency are the most important issues for future mobile systems. Heterogeneous networks (HetNets) with coordinated multiple points (CoMP) are wildly approved as a promising solution to meet increasing demands of mobile data traffic and to reduce energy consumptions. However, hyper-dense deployments and complex coordination mechanisms introduce several challenges in radio resource management (RRM) of mobile communication systems. To address this issue, we present an RRM approach for CoMP-based HetNets, which aims to maximize weighted energy efficiency while guaranteeing the data rate of each transmission. The proposed RRM approach is based on a cross-entropy (CE) optimization method that is an effective and low-complexity heuristic algorithm. Furthermore, we also give the implementations of the proposed RRM approach in centralized and decentralized mode, respectively. At last, extensive simulations are conducted to validate the effectiveness of the proposed schemes.Information2016-02-0271Article10.3390/info701000332078-24892016-02-02doi: 10.3390/info7010003Jia YuShinsuke KonakaMasatake AkutagawaQinyu Zhang<![CDATA[IJGI, Vol. 5, Pages 9: A Geosimulation Approach for Data Scarce Environments: Modeling Dynamics of Forest Insect Infestation across Different Landscapes]]>
http://www.mdpi.com/2220-9964/5/2/9
Insect infestation behaves as a complex system, characterized by non-linear spatial dynamics and emergent patterns that evolve from smaller to larger spatial scales. The emerald ash borer (EAB) is an invasive species that has infested and killed millions of ash trees across North America. Existing EAB models use traditional statistical approaches that often cannot address the spatiotemporal complexity emerging from EAB infestation processes. Moreover, these studies of insect infestation are limited by a lack of sufficient time series data. The objective of this study is to develop a geosimulation approach to overcome the challenge of data scarcity and represent EAB infestation at a regional scale. Geographic information systems (GIS), multi-criteria evaluation (MCE), and cellular automata (CA) are used to model EAB spread across different hypothetical landscape types. Simulation results represent EAB propagation and indicate different dynamics of spread for each landscape. Urban environments are identified as being at the greatest risk to the infestation. The proposed approach offers a theoretical framework and a modeling tool to represent the propagation of EAB infestation that can be applied with real geospatial datasets and potentially used in forest management strategies.ISPRS International Journal of Geo-Information2016-02-0252Article10.3390/ijgi502000992220-99642016-02-02doi: 10.3390/ijgi5020009Taylor AndersonSuzana Dragicevic<![CDATA[Mathematics, Vol. 4, Pages 5: Modular Forms and Weierstrass Mock Modular Forms]]>
http://www.mdpi.com/2227-7390/4/1/5
Alfes, Griffin, Ono, and Rolen have shown that the harmonic Maass forms arising from Weierstrass ζ-functions associated to modular elliptic curves “encode” the vanishing and nonvanishing for central values and derivatives of twisted Hasse-Weil L-functions for elliptic curves. Previously, Martin and Ono proved that there are exactly five weight 2 newforms with complex multiplication that are eta-quotients. In this paper, we construct a canonical harmonic Maass form for these five curves with complex multiplication. The holomorphic part of this harmonic Maass form arises from the Weierstrass ζ-function and is referred to as the Weierstrass mock modular form. We prove that the Weierstrass mock modular form for these five curves is itself an eta-quotient or a twist of one. Using this construction, we also obtain p-adic formulas for the corresponding weight 2 newform using Atkin’s U-operator.Mathematics2016-02-0241Article10.3390/math401000552227-73902016-02-02doi: 10.3390/math4010005Amanda Clemm<![CDATA[Information, Vol. 7, Pages 4: Closed-Loop Feedback Computation Model of Dynamical Reputation Based on the Local Trust Evaluation in Business-to-Consumer E-Commerce]]>
http://www.mdpi.com/2078-2489/7/1/4
Trust and reputation are important factors that influence the success of both traditional transactions in physical social networks and modern e-commerce in virtual Internet environments. It is difficult to define the concept of trust and quantify it because trust has both subjective and objective characteristics at the same time. A well-reported issue with reputation management system in business-to-consumer (BtoC) e-commerce is the “all good reputation” problem. In order to deal with the confusion, a new computational model of reputation is proposed in this paper. The ratings of each customer are set as basic trust score events. In addition, the time series of massive ratings are aggregated to formulate the sellers’ local temporal trust scores by Beta distribution. A logical model of trust and reputation is established based on the analysis of the dynamical relationship between trust and reputation. As for single goods with repeat transactions, an iterative mathematical model of trust and reputation is established with a closed-loop feedback mechanism. Numerical experiments on repeated transactions recorded over a period of 24 months are performed. The experimental results show that the proposed method plays guiding roles for both theoretical research into trust and reputation and the practical design of reputation systems in BtoC e-commerce.Information2016-02-0271Article10.3390/info701000442078-24892016-02-02doi: 10.3390/info7010004Bo TianJingti HanKecheng Liu<![CDATA[Electronics, Vol. 5, Pages 7: Effects of the Particle Size and the Solvent in Printing Inks on the Capacitance of Printed Parallel-Plate Capacitors]]>
http://www.mdpi.com/2079-9292/5/1/7
Parallel-plate capacitors were fabricated using a printed multi-layer structure in order to determine the effects of particle size and solvent on the capacitance. The conductive-dielectric-conductive layers were sequentially spun using commercial inks and by intermediate drying with the aid of a masking polymeric layer. Both optical and scanning electron microscopy were used to characterize the morphology of the printed layers. The measured capacitance was larger than the theoretically calculated value when ink with small-sized particles was used as the top plate. Furthermore, the use of a solvent whose polarity was similar to that of the underlying dielectric layer enhanced the penetration and resulted in an increase in capacitance. The functional resistance-capacitance low-pass filter was implemented using printed resistors and capacitors, a process that may be scalable in the future.Electronics2016-02-0251Article10.3390/electronics501000772079-92922016-02-02doi: 10.3390/electronics5010007Sungsik ParkDongjin Lee<![CDATA[Algorithms, Vol. 9, Pages 14: Two Efficient Derivative-Free Iterative Methods for Solving Nonlinear Systems]]>
http://www.mdpi.com/1999-4893/9/1/14
In this work, two multi-step derivative-free iterative methods are presented for solving system of nonlinear equations. The new methods have high computational efficiency and low computational cost. The order of convergence of the new methods is proved by a development of an inverse first-order divided difference operator. The computational efficiency is compared with the existing methods. Numerical experiments support the theoretical results. Experimental results show that the new methods remarkably reduce the computing time in the process of high-precision computing.Algorithms2016-02-0191Article10.3390/a9010014141999-48932016-02-01doi: 10.3390/a9010014Xiaofeng WangXiaodong Fan<![CDATA[Algorithms, Vol. 9, Pages 13: Algorithms for Managing, Querying and Processing Big Data in Cloud Environments]]>
http://www.mdpi.com/1999-4893/9/1/13
Big data (e.g., [1–3]) has become one of the most challenging research topics in current years. Big data is everywhere, from social networks to web advertisements, from sensor and stream systems to bio-informatics, from graph management tools to smart cities, and so forth. [...]Algorithms2016-02-0191Editorial10.3390/a9010013131999-48932016-02-01doi: 10.3390/a9010013Alfredo Cuzzocrea<![CDATA[IJGI, Vol. 5, Pages 8: Integrated WiFi/PDR/Smartphone Using an Adaptive System Noise Extended Kalman Filter Algorithm for Indoor Localization]]>
http://www.mdpi.com/2220-9964/5/2/8
Wireless signal strength is susceptible to the phenomena of interference, jumping, and instability, which often appear in the positioning results based on Wi-Fi field strength fingerprint database technology for indoor positioning. Therefore, a Wi-Fi and PDR (pedestrian dead reckoning) real-time fusion scheme is proposed in this paper to perform fusing calculation by adaptively determining the dynamic noise of a filtering system according to pedestrian movement (straight or turning), which can effectively restrain the jumping or accumulation phenomena of wireless positioning and the PDR error accumulation problem. Wi-Fi fingerprint matching typically requires a quite high computational burden: To reduce the computational complexity of this step, the affinity propagation clustering algorithm is adopted to cluster the fingerprint database and integrate the information of the position domain and signal domain of respective points. An experiment performed in a fourth-floor corridor at the School of Environment and Spatial Informatics, China University of Mining and Technology, shows that the traverse points of the clustered positioning system decrease by 65%–80%, which greatly improves the time efficiency. In terms of positioning accuracy, the average error is 4.09 m through the Wi-Fi positioning method. However, the positioning error can be reduced to 2.32 m after integration of the PDR algorithm with the adaptive noise extended Kalman filter (EKF).ISPRS International Journal of Geo-Information2016-02-0152Article10.3390/ijgi502000882220-99642016-02-01doi: 10.3390/ijgi5020008Xin LiJian WangChunyan LiuLiwen ZhangZhengkui Li<![CDATA[Robotics, Vol. 5, Pages 4: Sensor Fusion and Autonomy as a Powerful Combination for Biological Assessment in the Marine Environment]]>
http://www.mdpi.com/2218-6581/5/1/4
The ocean environment and the physical and biological processes that govern dynamics are complex. Sampling the ocean to better understand these processes is difficult given the temporal and spatial domains and sampling tools available. Biological systems are especially difficult as organisms possess behavior, operate at horizontal scales smaller than traditional shipboard sampling allows, and are often disturbed by the sampling platforms themselves. Sensors that measure biological processes have also generally not kept pace with the development of physical counterparts as their requirements are as complex as the target organisms. Here, we attempt to address this challenge by advocating the need for sensor-platform combinations to integrate and process data in real-time and develop data products that are useful in increasing sampling efficiencies. Too often, the data of interest is only garnered after post-processing after a sampling effort and the opportunity to use that information to guide sampling is lost. Here we demonstrate a new autonomous platform, where data are collected, analyzed, and data products are output in real-time to inform autonomous decision-making. This integrated capability allows for enhanced and informed sampling towards improving our understanding of the marine environment.Robotics2016-02-0151Article10.3390/robotics501000442218-65812016-02-01doi: 10.3390/robotics5010004Mark MolineKelly Benoit-Bird<![CDATA[Axioms, Vol. 5, Pages 5: Modular Nuclearity: A Generally Covariant Perspective]]>
http://www.mdpi.com/2075-1680/5/1/5
A quantum field theory in its algebraic description may admit many irregular states. So far, selection criteria to distinguish physically reasonable states have been restricted to free fields (Hadamard condition) or to flat spacetimes (e.g., Buchholz-Wichmann nuclearity). We propose instead to use a modular ℓp -condition, which is an extension of a strengthened modular nuclearity condition to generally covariant theories. The modular nuclearity condition was previously introduced in Minkowski space, where it played an important role in constructive two dimensional algebraic QFT’s. We show that our generally covariant extension of this condition makes sense for a vast range of theories, and that it behaves well under causal propagation and taking mixtures. In addition we show that our modular ℓp -condition holds for every quasi-free Hadamard state of a free scalar quantum field (regardless of mass or scalar curvature coupling). However, our condition is not equivalent to the Hadamard condition.Axioms2016-01-2951Article10.3390/axioms501000552075-16802016-01-29doi: 10.3390/axioms5010005Gandalf LechnerKo Sanders<![CDATA[Systems, Vol. 4, Pages 11: The Relation of Shadow Systems and ERP Systems—Insights from a Multiple-Case Study]]>
http://www.mdpi.com/2079-8954/4/1/11
ERP systems integrate a major part of all business processes and organizations include them in their IT service management. Besides these formal systems, there are additional systems that are rather stand-alone and not included in the IT management tasks. These so-called ‘shadow systems’ also support business processes but hinder a high enterprise integration. Shadow systems appear during their explicit detection or during software maintenance projects such as enhancements or release changes of enterprise systems. Organizations then have to decide if and to what extent they integrate the identified shadow systems into their ERP systems. For this decision, organizations have to compare the capabilities of each identified shadow system with their ERP systems. Based on multiple-case studies, we provide a dependency approach to enable their comparison. We derive categories for different stages of the dependency and base insights into integration possibilities on these stages. Our results show that 64% of the shadow systems in our case studies are related to ERP systems. This means that they share parts or all of their data and/or functionality with the ERP system. Our research contributes to the field of integration as well as to the discussion about shadow systems.Systems2016-01-2941Article10.3390/systems4010011112079-89542016-01-29doi: 10.3390/systems4010011Melanie HuberStephan ZimmermannChristopher RentropCarsten Felden<![CDATA[Technologies, Vol. 4, Pages 4: Single Atoms Preparation Using Light-Assisted Collisions]]>
http://www.mdpi.com/2227-7080/4/1/4
The detailed control achieved over single optically trapped neutral atoms makes them candidates for applications in quantum metrology and quantum information processing. The last few decades have seen different methods developed to optimize the preparation efficiency of single atoms in optical traps. Here we review the near-deterministic preparation of single atoms based on light-assisted collisions and describe how this method can be implemented in different trap regimes. The simplicity and versatility of the method makes it feasible to be employed in future quantum technologies such as a quantum logic device.Technologies2016-01-2741Review10.3390/technologies401000442227-70802016-01-27doi: 10.3390/technologies4010004Yin FungPimonpan SompetMikkel Andersen<![CDATA[Future Internet, Vol. 8, Pages 4: Context-Based Energy Disaggregation in Smart Homes]]>
http://www.mdpi.com/1999-5903/8/1/4
In this paper, we address the problem of energy conservation and optimization in residential environments by providing users with useful information to solicit a change in consumption behavior. Taking care to highly limit the costs of installation and management, our work proposes a Non-Intrusive Load Monitoring (NILM) approach, which consists of disaggregating the whole-house power consumption into the individual portions associated to each device. State of the art NILM algorithms need monitoring data sampled at high frequency, thus requiring high costs for data collection and management. In this paper, we propose an NILM approach that relaxes the requirements on monitoring data since it uses total active power measurements gathered at low frequency (about 1 Hz). The proposed approach is based on the use of Factorial Hidden Markov Models (FHMM) in conjunction with context information related to the user presence in the house and the hourly utilization of appliances. Through a set of tests, we investigated how the use of these additional context-awareness features could improve disaggregation results with respect to the basic FHMM algorithm. The tests have been performed by using Tracebase, an open dataset made of data gathered from real home environments.Future Internet2016-01-2781Article10.3390/fi801000441999-59032016-01-27doi: 10.3390/fi8010004Francesca ParadisoFederica PaganelliDino GiuliSamuele Capobianco<![CDATA[Axioms, Vol. 5, Pages 4: Data Farming Process and Initial Network Analysis Capabilities]]>
http://www.mdpi.com/2075-1680/5/1/4
Data Farming, network applications and approaches to integrate network analysis and processes to the data farming paradigm are presented as approaches to address complex system questions. Data Farming is a quantified approach that examines questions in large possibility spaces using modeling and simulation. It evaluates whole landscapes of outcomes to draw insights from outcome distributions and outliers. Social network analysis and graph theory are widely used techniques for the evaluation of social systems. Incorporation of these techniques into the data farming process provides analysts examining complex systems with a powerful new suite of tools for more fully exploring and understanding the effect of interactions in complex systems. The integration of network analysis with data farming techniques provides modelers with the capability to gain insight into the effect of network attributes, whether the network is explicitly defined or emergent, on the breadth of the model outcome space and the effect of model inputs on the resultant network statistics.Axioms2016-01-2751Article10.3390/axioms501000442075-16802016-01-27doi: 10.3390/axioms5010004Gary HorneTheodore Meyer<![CDATA[Algorithms, Vol. 9, Pages 12: Integrating Pareto Optimization into Dynamic Programming]]>
http://www.mdpi.com/1999-4893/9/1/12
Pareto optimization combines independent objectives by computing the Pareto front of the search space, yielding a set of optima where none scores better on all objectives than any other. Recently, it was shown that Pareto optimization seamlessly integrates with algebraic dynamic programming: when scoring schemes A and B can correctly evaluate the search space via dynamic programming, then so can Pareto optimization with respect to A and B. However, the integration of Pareto optimization into dynamic programming opens a wide range of algorithmic alternatives, which we study in substantial detail in this article, using real-world applications in biosequence analysis, a field where dynamic programming is ubiquitous. Our results are two-fold: (1) We introduce the operation of a “Pareto algebra product” in the dynamic programming framework of Bellman’s GAP. Users of this framework can now ask for Pareto optimization with a single keystroke. Careful evaluation of the implementation alternatives by means of an extended Bellman’s GAP compiler demonstrates the dependence of the best implementation choice on the application at hand. (2) We extract from our experiments several pieces of advice to programmers who do not use a system such as Bellman’s GAP, but who choose to hand-craft their dynamic programming recurrences, incorporating Pareto optimization from scratch.Algorithms2016-01-2791Article10.3390/a9010012121999-48932016-01-27doi: 10.3390/a9010012Thomas GatterRobert GiegerichCédric Saule<![CDATA[JSAN, Vol. 5, Pages 1: Acknowledgement to Reviewers of JSAN in 2015]]>
http://www.mdpi.com/2224-2708/5/1/1
The editors of JSAN would like to express their sincere gratitude to the following reviewers for assessing manuscripts in 2015. [...]Journal of Sensor and Actuator Networks2016-01-2751Editorial10.3390/jsan501000112224-27082016-01-27doi: 10.3390/jsan5010001 JSAN Editorial Office<![CDATA[Computation, Vol. 4, Pages 5: Extracting Conformational Ensembles of Small Molecules from Molecular Dynamics Simulations: Ampicillin as a Test Case]]>
http://www.mdpi.com/2079-3197/4/1/5
The accurate and exhaustive description of the conformational ensemble sampled by small molecules in solution, possibly at different physiological conditions, is of primary interest in many fields of medicinal chemistry and computational biology. Recently, we have built an on-line database of compounds with antimicrobial properties, where we provide all-atom force-field parameters and a set of molecular properties, including representative structures extracted from cluster analysis over μs-long molecular dynamics (MD) trajectories. In the present work, we used a medium-sized antibiotic from our sample, namely ampicillin, to assess the quality of the conformational ensemble. To this aim, we compared the conformational landscape extracted from previous unbiased MD simulations to those obtained by means of Replica Exchange MD (REMD) and those originating from three freely-available conformer generation tools widely adopted in computer-aided drug-design. In addition, for different charge/protonation states of ampicillin, we made available force-field parameters and static/dynamic properties derived from both Density Functional Theory and MD calculations. For the specific system investigated here, we found that: (i) the conformational statistics extracted from plain MD simulations is consistent with that obtained from REMD simulations; (ii) overall, our MD-based approach performs slightly better than any of the conformer generator tools if one takes into account both the diversity of the generated conformational set and the ability to reproduce experimentally-determined structures.Computation2016-01-2641Article10.3390/computation401000552079-31972016-01-26doi: 10.3390/computation4010005Giuliano MallociGiovanni SerraAndrea BosinAttilio Vargiu<![CDATA[Systems, Vol. 4, Pages 10: Challenges while Updating Planning Parameters of an ERP System and How a Simulation-Based Support System Can Support Material Planners]]>
http://www.mdpi.com/2079-8954/4/1/10
In an Enterprise Resource Planning (ERP) system, production planning is influenced by a variety of parameters. Previous investigations show that setting parameter values is highly relevant to a company’s target system. Parameter settings should be checked and adjusted, e.g., after a change in environmental factors, by material planners. In practice, updating the parameters is difficult due to several reasons. This paper presents a simulation-based decision support system, which helps material planners in all stages of decision-making processes. It will present the system prototype’s user interface and the results of applying the system to a case study.Systems2016-01-2641Article10.3390/systems4010010102079-89542016-01-26doi: 10.3390/systems4010010Ulrike StumvollThorsten Claus<![CDATA[Systems, Vol. 4, Pages 8: An Approach to Represent and Communicate Product or System Design Ideas at the Fuzzy-Front End of the Design Process]]>
http://www.mdpi.com/2079-8954/4/1/8
The primary challenge underscored and dealt with was how to represent the product’s or system’s use environment and processes and to communicate ideas and envisaged use contexts effectively at the fuzzy-front early stages of the design process. The work focused specifically on complex products or systems with physical, software and/or cyber components, and the question was how to represent, e.g., the operations of the product or system and the interactions between the user and the product or system betimes in the period between when an opportunity for a new product or system is first considered, and when the idea is judged to be ready to enter formal development. Several approaches are currently being used to express and to communicate ideas at the conceptualization, embodiment, and detail design stages of the design process, but none of them address the challenge described above. We therefore adapted and extended the abstract prototyping concept to allow for total representation of ideas, as well as of use environments and processes early on. Extended abstract prototyping (Ext-AP) entails using combinations of low and high-fidelity prototyping techniques to create cognitive virtual representations, which represent and help designers to express ideas and use contexts—namely, what complex product or system would be like, and how its users would interact with it. Real-world product development case studies have been used to demonstrate how the Ext-AP technique can be put into practice. One of the main observations from the application case studies is that the Ext-AP technique enabled the subjects to express ideas and use contexts more effectively early on. In addition, the extended abstract prototypes (Ext-APs) offered a low cost, yet effective solution for expressing ideas, representing concepts and using contexts, and allowed the subjects to think divergently, make associations, easily and quickly construct, combine, and evaluate alternatives, and work together on multiple ideas simultaneously.Systems2016-01-2641Technical Note10.3390/systems401000882079-89542016-01-26doi: 10.3390/systems4010008Eliab Opiyo<![CDATA[Symmetry, Vol. 8, Pages 7: On the Boundedness and Symmetry Properties of the Fractal Sets Generated from Alternated Complex Map]]>
http://www.mdpi.com/2073-8994/8/2/7
A complex map can give rise to two kinds of fractal sets: the Julia sets and the parameters sets (or the connectivity loci) which represent different connectivity properties of the corresponding Julia sets. In the significative results of (Int. J. Bifurc. Chaos, 2009, 19:2123–2129) and (Nonlinear. Dyn. 2013, 73:1155–1163), the authors presented the two kinds of fractal sets of a class of alternated complex map and left some visually observations to be proved about the boundedness and symmetry properties of these fractal sets. In this paper, we improve the previous results by giving the strictly mathematical proofs of the two properties. Some simulations that verify the theoretical proofs are also included.Symmetry2016-01-2682Article10.3390/sym802000772073-89942016-01-26doi: 10.3390/sym8020007Da WangShuTang Liu<![CDATA[Systems, Vol. 4, Pages 9: “Space, the Final Frontier”: How Good are Agent-Based Models at Simulating Individuals and Space in Cities?]]>
http://www.mdpi.com/2079-8954/4/1/9
Cities are complex systems, comprising of many interacting parts. How we simulate and understand causality in urban systems is continually evolving. Over the last decade the agent-based modeling (ABM) paradigm has provided a new lens for understanding the effects of interactions of individuals and how through such interactions macro structures emerge, both in the social and physical environment of cities. However, such a paradigm has been hindered due to computational power and a lack of large fine scale datasets. Within the last few years we have witnessed a massive increase in computational processing power and storage, combined with the onset of Big Data. Today geographers find themselves in a data rich era. We now have access to a variety of data sources (e.g., social media, mobile phone data, etc.) that tells us how, and when, individuals are using urban spaces. These data raise several questions: can we effectively use them to understand and model cities as complex entities? How well have ABM approaches lent themselves to simulating the dynamics of urban processes? What has been, or will be, the influence of Big Data on increasing our ability to understand and simulate cities? What is the appropriate level of spatial analysis and time frame to model urban phenomena? Within this paper we discuss these questions using several examples of ABM applied to urban geography to begin a dialogue about the utility of ABM for urban modeling. The arguments that the paper raises are applicable across the wider research environment where researchers are considering using this approach.Systems2016-01-2641Article10.3390/systems401000992079-89542016-01-26doi: 10.3390/systems4010009Alison HeppenstallNick MallesonAndrew Crooks<![CDATA[Mathematics, Vol. 4, Pages 4: Acknowledgement to Reviewers of Mathematics in 2015]]>
http://www.mdpi.com/2227-7390/4/1/4
The editors of Mathematics would like to express their sincere gratitude to the following reviewers for assessing manuscripts in 2015. [...]Mathematics2016-01-2541Editorial10.3390/math401000442227-73902016-01-25doi: 10.3390/math4010004 Mathematics Editorial Office<![CDATA[Administrative Sciences, Vol. 6, Pages 2: Acknowledgement to Reviewers of Administrative Sciences in 2015]]>
http://www.mdpi.com/2076-3387/6/1/2
The editors of Administrative Sciences would like to express their sincere gratitude to the following reviewers for assessing manuscripts in 2015. [...]Administrative Sciences2016-01-2561Editorial10.3390/admsci601000222076-33872016-01-25doi: 10.3390/admsci6010002 Administrative Sciences Editorial Office<![CDATA[Axioms, Vol. 5, Pages 3: Acknowledgement to Reviewers of Axioms in 2015]]>
http://www.mdpi.com/2075-1680/5/1/3
The editors of Axioms would like to express their sincere gratitude to the following reviewers for assessing manuscripts in 2015. [...]Axioms2016-01-2551Editorial10.3390/axioms501000332075-16802016-01-25doi: 10.3390/axioms5010003 Axioms Editorial Office<![CDATA[Econometrics, Vol. 4, Pages 5: Acknowledgement to Reviewers of Econometrics in 2015]]>
http://www.mdpi.com/2225-1146/4/1/5
The editors of Econometrics would like to express their sincere gratitude to the following reviewers for assessing manuscripts in 2015. [...]Econometrics2016-01-2541Editorial10.3390/econometrics401000552225-11462016-01-25doi: 10.3390/econometrics4010005 Econometrics Editorial Office<![CDATA[Future Internet, Vol. 8, Pages 3: Acknowledgement to Reviewers of Future Internet in 2015]]>
http://www.mdpi.com/1999-5903/8/1/3
The editors of Future Internet would like to express their sincere gratitude to the following reviewers for assessing manuscripts in 2015. [...]Future Internet2016-01-2281Editorial10.3390/fi801000331999-59032016-01-22doi: 10.3390/fi8010003 Future Internet Editorial Office<![CDATA[IJFS, Vol. 4, Pages 2: Acknowledgement to Reviewers of the International Journal of Financial Studies in 2015]]>
http://www.mdpi.com/2227-7072/4/1/2
The editors of the International Journal of Financial Studies Editorial Office, would like to express their sincere gratitude to the following reviewers for assessing manuscripts in 2015. [...]International Journal of Financial Studies2016-01-2241Editorial10.3390/ijfs401000222227-70722016-01-22doi: 10.3390/ijfs4010002 International Journal of Financial Studies Editorial Office<![CDATA[Economies, Vol. 4, Pages 2: Acknowledgement to Reviewers of Economies in 2015]]>
http://www.mdpi.com/2227-7099/4/1/2
The editors of Economies would like to express their sincere gratitude to the following reviewers for assessing manuscripts in 2015. [...]Economies2016-01-2241Editorial10.3390/economies401000222227-70992016-01-22doi: 10.3390/economies4010002 Economies Editorial Office<![CDATA[Robotics, Vol. 5, Pages 3: Acknowledgement to Reviewers of Robotics in 2015]]>
http://www.mdpi.com/2218-6581/5/1/3
The editors of Robotics would like to express their sincere gratitude to the following reviewers for assessing manuscripts in 2015. [...]Robotics2016-01-2251Editorial10.3390/robotics501000332218-65812016-01-22doi: 10.3390/robotics5010003 Robotics Editorial Office<![CDATA[Economies, Vol. 4, Pages 1: Falling Behind, Forging Ahead and Falling Behind Again: Thailand from 1870 to 2014]]>
http://www.mdpi.com/2227-7099/4/1/1
The paper argues that Thailand’s economic and social development from the late 19th century to the early 21st century presents a puzzle. For much of the period from 1870 to 1940, the country’s economic growth was slow, and the economy remained agricultural, with little diversification into modern industry or services. It was the only Southeast Asian country to escape direct colonization, and yet it did not use its relative freedom from colonial control to embark on a programme of accelerated economic, social and political modernization. The contrast with Meiji Japan has been made by several Thai and foreign scholars, but Thailand’s growth was also slow in comparison with several neighbouring countries under colonial control. Only in the late 1950s did economic growth start to accelerate and by 1996, per capita GDP was well ahead of other ASEAN countries except Malaysia and Singapore. The paper explores the reasons for the accelerated growth, looking particularly at the role of government. The paper also examines the reasons for the growth collapse of 1997/1998, and the slower economic growth since then.Economies2016-01-2241Article10.3390/economies401000112227-70992016-01-22doi: 10.3390/economies4010001Anne Booth<![CDATA[Algorithms, Vol. 9, Pages 11: Acknowledgement to Reviewers of Algorithms in 2015]]>
http://www.mdpi.com/1999-4893/9/1/11
The editors of Algorithms would like to express their sincere gratitude to the following reviewers for assessing manuscripts in 2015. [...]Algorithms2016-01-2291Editorial10.3390/a9010011111999-48932016-01-22doi: 10.3390/a9010011 Algorithms Editorial Office<![CDATA[Computation, Vol. 4, Pages 4: Acknowledgement to Reviewers of Computation in 2015]]>
http://www.mdpi.com/2079-3197/4/1/4
The editors of Computation would like to express their sincere gratitude to the following reviewers for assessing manuscripts in 2015. [...]Computation2016-01-2241Editorial10.3390/computation401000442079-31972016-01-22doi: 10.3390/computation4010004 Computation Editorial Office<![CDATA[Systems, Vol. 4, Pages 7: Acknowledgement to Reviewers of Systems in 2015]]>
http://www.mdpi.com/2079-8954/4/1/7
The editors of Systems would like to express their sincere gratitude to the following reviewers for assessing manuscripts in 2015. [...]Systems2016-01-2241Editorial10.3390/systems401000772079-89542016-01-22doi: 10.3390/systems4010007 Systems Editorial Office<![CDATA[Algorithms, Vol. 9, Pages 10: An Optimal Order Method for Multiple Roots in Case of Unknown Multiplicity]]>
http://www.mdpi.com/1999-4893/9/1/10
In the literature, recently, some three-step schemes involving four function evaluations for the solution of multiple roots of nonlinear equations, whose multiplicity is not known in advance, are considered, but they do not agree with Kung–Traub’s conjecture. The present article is devoted to the study of an iterative scheme for approximating multiple roots with a convergence rate of eight, when the multiplicity is hidden, which agrees with Kung–Traub’s conjecture. The theoretical study of the convergence rate is investigated and demonstrated. A few nonlinear problems are presented to justify the theoretical study.Algorithms2016-01-2291Article10.3390/a9010010101999-48932016-01-22doi: 10.3390/a9010010Jai Jaiswal<![CDATA[Technologies, Vol. 4, Pages 3: Acknowledgement to Reviewers of Technologies in 2015]]>
http://www.mdpi.com/2227-7080/4/1/3
The editors of Technologies would like to express their sincere gratitude to the following reviewers for assessing manuscripts in 2015. [...]Technologies2016-01-2241Editorial10.3390/technologies401000332227-70802016-01-22doi: 10.3390/technologies4010003 Technologies Editorial Office<![CDATA[Electronics, Vol. 5, Pages 6: Acknowledgement to Reviewers of Electronics in 2015]]>
http://www.mdpi.com/2079-9292/5/1/6
The editors of Electronics would like to express their sincere gratitude to the following reviewers for assessing manuscripts in 2015. [...]Electronics2016-01-2251Editorial10.3390/electronics501000662079-92922016-01-22doi: 10.3390/electronics5010006 Electronics Editorial Office<![CDATA[Risks, Vol. 4, Pages 1: Acknowledgement to Reviewers of Risks in 2015]]>
http://www.mdpi.com/2227-9091/4/1/1
The editors of Risks would like to express their sincere gratitude to the following reviewers for assessing manuscripts in 2015. [...]Risks2016-01-2141Editorial10.3390/risks401000112227-90912016-01-21doi: 10.3390/risks4010001 Risks Editorial Office<![CDATA[Computers, Vol. 5, Pages 2: Acknowledgement to Reviewers of Computers in 2015]]>
http://www.mdpi.com/2073-431X/5/1/2
The editors of Computers would like to express their sincere gratitude to the following reviewers for assessing manuscripts in 2015. [...]Computers2016-01-2151Editorial10.3390/computers501000222073-431X2016-01-21doi: 10.3390/computers5010002 Computers Editorial Office<![CDATA[Information, Vol. 7, Pages 2: Acknowledgement to Reviewers of Information in 2015]]>
http://www.mdpi.com/2078-2489/7/1/2
The editors of Information would like to express their sincere gratitude to the following reviewers for assessing manuscripts in 2015. [...]Information2016-01-2171Editorial10.3390/info701000222078-24892016-01-21doi: 10.3390/info7010002 Information Editorial Office<![CDATA[IJGI, Vol. 5, Pages 7: Acknowledgement to Reviewers of ISPRS International Journal of Geo-Information in 2015]]>
http://www.mdpi.com/2220-9964/5/1/7
The editors of ISPRS International Journal of Geo-Information would like to express their sincere gratitude to the following reviewers for assessing manuscripts in 2015. [...]ISPRS International Journal of Geo-Information2016-01-2151Editorial10.3390/ijgi501000772220-99642016-01-21doi: 10.3390/ijgi5010007 IJGI Editorial Office<![CDATA[Symmetry, Vol. 8, Pages 6: Acknowledgement to Reviewers of Symmetry in 2015]]>
http://www.mdpi.com/2073-8994/8/1/6
The editors of Symmetry would like to express their sincere gratitude to the following reviewers for assessing manuscripts in 2015. [...]Symmetry2016-01-2181Editorial10.3390/sym801000662073-89942016-01-21doi: 10.3390/sym8010006Symmetry Editorial Office<![CDATA[Symmetry, Vol. 8, Pages 5: Symmetry in Sphere-Based Assembly Configuration Spaces]]>
http://www.mdpi.com/2073-8994/8/1/5
Many remarkably robust, rapid and spontaneous self-assembly phenomena occurring in nature can be modeled geometrically, starting from a collection of rigid bunches of spheres. This paper highlights the role of symmetry in sphere-based assembly processes. Since spheres within bunches could be identical and bunches could be identical, as well, the underlying symmetry groups could be of large order that grows with the number of participating spheres and bunches. Thus, understanding symmetries and associated isomorphism classes of microstates that correspond to various types of macrostates can significantly increase efficiency and accuracy, i.e., reduce the notorious complexity of computing entropy and free energy, as well as paths and kinetics, in high dimensional configuration spaces. In addition, a precise understanding of symmetries is crucial for giving provable guarantees of algorithmic accuracy and efficiency, as well as accuracy vs. efficiency trade-offs in such computations. In particular, this may aid in predicting crucial assembly-driving interactions. This is a primarily expository paper that develops a novel, original framework for dealing with symmetries in configuration spaces of assembling spheres, with the following goals. (1) We give new, formal definitions of various concepts relevant to the sphere-based assembly setting that occur in previous work and, in turn, formal definitions of their relevant symmetry groups leading to the main theorem concerning their symmetries. These previously-developed concepts include, for example: (i) assembly configuration spaces; (ii) stratification of assembly configuration space into configurational regions defined by active constraint graphs; (iii) paths through the configurational regions; and (iv) coarse assembly pathways. (2) We then demonstrate the new symmetry concepts to compute the sizes and numbers of orbits in two example settings appearing in previous work. (3) Finally, we give formal statements of a variety of open problems and challenges using the new conceptual definitions.Symmetry2016-01-2181Article10.3390/sym801000552073-89942016-01-21doi: 10.3390/sym8010005Meera SitharamAndrew VinceMenghan WangMiklós Bóna<![CDATA[Mathematics, Vol. 4, Pages 3: Multiplicative Expression for the Coefficient in Fermionic 3–3 Relation]]>
http://www.mdpi.com/2227-7390/4/1/3
Recently, a family of fermionic relations were discovered corresponding to Pachner move 3–3 and parameterized by complex-valued 2-cocycles, where the weight of a pentachoron (4-simplex) is a Grassmann–Gaussian exponent. Here, the proportionality coefficient between Berezin integrals in the l.h.s. and r.h.s. of such relations is written in a form multiplicative over simplices.Mathematics2016-01-2041Article10.3390/math401000332227-73902016-01-20doi: 10.3390/math4010003Igor Korepanov<![CDATA[Future Internet, Vol. 8, Pages 2: Detection of Intelligent Intruders in Wireless Sensor Networks]]>
http://www.mdpi.com/1999-5903/8/1/2
Most of the existing research works on the intrusion detection problem in a wireless sensor network (WSN) assume linear or random mobility patterns in abstracting intruders’ models in traversing the WSN field. However, in real-life WSN applications, an intruder is usually an intelligent mobile robot with environment learning and detection avoidance capability (i.e., the capability to avoid surrounding sensors). Due to this, the literature results based on the linear or random mobility models may not be applied to the real-life WSN design and deployment for efficient and effective intrusion detection in practice. This motivates us to investigate the impact of intruder’s intelligence on the intrusion detection problem in a WSN for various applications. To be specific, we propose two intrusion algorithms, the pinball and flood-fill algorithms, to mimic the intelligent motion and behaviors of a mobile intruder in detecting and circumventing nearby sensors for detection avoidance while heading for its destination. The two proposed algorithms are integrated into a WSN framework for intrusion detection analysis in various circumstances. Monte Carlo simulations are conducted, and the results indicate that: (1) the performance of a WSN drastically changes as a result of the intruder’s intelligence in avoiding sensor detections and intrusion algorithms; (2) network parameters, including node density, sensing range and communication range, play a crucial part in the effectiveness of the intruder’s intrusion algorithms; and (3) it is imperative to integrate intruder’s intelligence in the WSN research for intruder detection problems under various application circumstances.Future Internet2016-01-2081Article10.3390/fi801000221999-59032016-01-20doi: 10.3390/fi8010002Yun WangWilliam ChuSarah FieldsColleen HeinemannZach Reiter<![CDATA[Systems, Vol. 4, Pages 6: A Hierarchical Aggregation Approach for Indicators Based on Data Envelopment Analysis and Analytic Hierarchy Process]]>
http://www.mdpi.com/2079-8954/4/1/6
This research proposes a hierarchical aggregation approach using Data Envelopment Analysis (DEA) and Analytic Hierarchy Process (AHP) for indicators. The core logic of the proposed approach is to reflect the hierarchical structures of indicators and their relative priorities in constructing composite indicators (CIs), simultaneously. Under hierarchical structures, the indicators of similar characteristics can be grouped into sub-categories and further into categories. According to this approach, we define a domain of composite losses, i.e., a reduction in CI values, based on two sets of weights. The first set represents the weights of indicators for each Decision Making Unit (DMU) with the minimal composite loss, and the second set represents the weights of indicators bounded by AHP with the maximal composite loss. Using a parametric distance model, we explore various ranking positions for DMUs while the indicator weights obtained from a three-level DEA-based CI model shift towards the corresponding weights bounded by AHP. An illustrative example of road safety performance indicators (SPIs) for a set of European countries highlights the usefulness of the proposed approach.Systems2016-01-2041Article10.3390/systems401000662079-89542016-01-20doi: 10.3390/systems4010006Mohammad Pakkar<![CDATA[Information, Vol. 7, Pages 1: Hierarchy and the Nature of Information]]>
http://www.mdpi.com/2078-2489/7/1/1
We address the nature of information from a systemic structural point of view. Starting from the Natural hierarchy of living systems, we elucidate its decomposition into two partial hierarchies associated with its extant levels and inter-level regions, respectively. External observation of a hierarchical system involves the generation of approximate hyperscalar representations of these two partials, which then reintegrate to give a singular metascalar result. We relate Havel’s categories of reality and Peirce’s categories of experience to this result, and indicate that the ultimate result of the reintegration of hyperscalar data and context is a sign which is information.Information2016-01-2071Article10.3390/info701000112078-24892016-01-20doi: 10.3390/info7010001Ron CottamWilly RansonRoger Vounckx<![CDATA[Computation, Vol. 4, Pages 3: A Test of Various Partial Atomic Charge Models for Computations on Diheteroaryl Ketones and Thioketones]]>
http://www.mdpi.com/2079-3197/4/1/3
The effective use of partial atomic charge models is essential for such purposes in molecular computations as a simplified representation of global charge distribution in a molecule and predicting its conformational behavior. In this work, ten of the most popular models of partial atomic charge are taken into consideration, and these models operate on the molecular wave functions/electron densities of five diheteroaryl ketones and their thiocarbonyl analogs. The ten models are tested in order to assess their usefulness in achieving the aforementioned purposes for the compounds in title. Therefore, the following criteria are used in the test: (1) how accurately these models reproduce the molecular dipole moments of the conformers of the investigated compounds; (2) whether these models are able to correctly determine the preferred conformer as well as the ordering of higher-energy conformers for each compound. The results of the test indicate that the Merz-Kollman-Singh (MKS) and Hu-Lu-Yang (HLY) models approximate the magnitude of the molecular dipole moments with the greatest accuracy. The natural partial atomic charges perform best in determining the conformational behavior of the investigated compounds. These findings may constitute important support for the effective computations of electrostatic effects occurring within and between the molecules of the compounds in question as well as similar compounds.Computation2016-01-1941Article10.3390/computation401000332079-31972016-01-19doi: 10.3390/computation4010003Piotr Matczak<![CDATA[IJGI, Vol. 5, Pages 6: Segmentation of Façades from Urban 3D Point Clouds Using Geometrical and Morphological Attribute-Based Operators]]>
http://www.mdpi.com/2220-9964/5/1/6
3D building segmentation is an important research issue in the remote sensing community with relevant applications to urban modeling, cloud-to-cloud and cloud-to-model registration, 3D cartography, virtual reality, cultural heritage documentation, among others. In this paper, we propose automatic, parametric and robust approaches to segment façades from 3D point clouds. Processing is carried out using elevation images and 3D decomposition, and the final result can be reprojected onto the 3D point cloud for visualization or evaluation purposes. Our methods are based on geometrical and geodesic constraints. Parameters are related to urban and architectural constraints. Thus, they can be set up to manage façades of any height, length and elongation. We propose two methods based on façade marker extraction and a third method without markers based on the maximal elongation image. This work is developed in the framework of TerraMobilita project. The performance of our methods is proved in our experiments on TerraMobilita databases using 2D and 3D ground truth annotations.ISPRS International Journal of Geo-Information2016-01-1951Article10.3390/ijgi501000662220-99642016-01-19doi: 10.3390/ijgi5010006Andrés SernaBeatriz MarcoteguiJorge Hernández<![CDATA[Algorithms, Vol. 9, Pages 9: NBTI-Aware Transient Fault Rate Analysis Method for Logic Circuit Based on Probability Voltage Transfer Characteristics]]>
http://www.mdpi.com/1999-4893/9/1/9
The reliability of Very Large Scale Integration (VLSI) circuits has become increasingly susceptible to transient faults induced by environmental noise with the scaling of technology. Some commonly used fault tolerance strategies require statistical methods to accurately estimate the fault rate in different parts of the logic circuit, and Monte Carlo (MC) simulation is often applied to complete this task. However, the MC method suffers from impractical computation costs due to the size of the circuits. Furthermore, circuit aging effects, such as negative bias temperature instability (NBTI), will change the characteristics of the circuit during its lifetime, leading to a change in the circuit’s noise margin. This change will increase the complexity of transient fault rate estimation tasks. In this paper, an NBTI-aware statistical analysis method based on probability voltage transfer characteristics is proposed for combinational logic circuit. This method can acquire accurate fault rates using a discrete probability density function approximation process, thus resolving the computation cost problem of the MC method. The proposed method can also consider aging effects and analyze statistical changes in the fault rates. Experimental results demonstrate that, compared to the MC simulation, our method can achieve computation times that are two orders of magnitude shorter while maintaining an error rate less than 9%.Algorithms2016-01-1891Article10.3390/a901000991999-48932016-01-18doi: 10.3390/a9010009Zhiming YangJunbao LiYang YuXiyuan Peng<![CDATA[IJGI, Vol. 5, Pages 5: Temporal Analysis on Contribution Inequality in OpenStreetMap: A Comparative Study for Four Countries]]>
http://www.mdpi.com/2220-9964/5/1/5
Contribution inequality widely exists in OpenStreetMap (OSM), which means that most data come from a minority of the contributors, while the majority only accounts for a small percentage of data. This phenomenon is of great importance to understanding from where the data come and how the project evolves. The investigation in this paper is dedicated to answering the following questions: How does contribution inequality change over time in OSM? Which group of contributors plays a more important role in influencing trends in contribution inequality: the “vocal minority” or the “silent majority”? To answer the first question, we provide overall measurements for contribution inequality using the Lorenz curve and the Gini coefficient. To answer the second question, we use quantile-based classifying strategy to analyze structural changes in the community, and use the Mann-Whitney-Wilcoxon test to analyze productivity changes. Our case study shows that in countries without significant imports, contributions become more unequal over time. This trend is consistent with the rapid expansion of the silent majority, even though other classes of contributors also grow at a slower pace. On the other hand, contribution inequality fluctuates a lot in countries with huge imports, and agrees well with the productivity changes in the vocal minority.ISPRS International Journal of Geo-Information2016-01-1851Article10.3390/ijgi501000552220-99642016-01-18doi: 10.3390/ijgi5010005Anran YangHongchao FanNing JingYeran SunAlexander Zipf<![CDATA[Systems, Vol. 4, Pages 5: Exploring Intra-Urban Accessibility and Impacts of Pollution Policies with an Agent-Based Simulation Platform: GaMiroD]]>
http://www.mdpi.com/2079-8954/4/1/5
In this work we address the issue of sustainable cities by focusing on one of their very central components: daily mobility. Indeed, if cities can be interpreted as spatial organizations allowing social interactions, the number of daily movements needed to reach this goal is continuously increasing. Therefore, improving urban accessibility merely results in increasing traffic and its negative externalities (congestion, accidents, pollution, noise, etc.), while eventually reducing the quality of life of people in the city. This is why several urban-transport policies are implemented in order to reduce individual mobility impacts while maintaining equitable access to the city. This challenge is however non-trivial and therefore we propose to investigate this issue from the complex systems point of view. The real spatial-temporal urban accessibility of citizens cannot be approximated just by focusing on space and implies taking into account the space-time activity patterns of individuals, in a more dynamic way. Thus, given the importance of local interactions in such a perspective, an agent based approach seems to be a relevant solution. This kind of individual based and “interactionist” approach allows us to explore the possible impact of individual behaviors on the overall dynamics of the city but also the possible impact of global measures on individual behaviors. In this paper, we give an overview of the Miro Project and then focus on the GaMiroD model design from real data analysis to model exploration tuned by transportation-oriented scenarios. Among them, we start with the the impact of a LEZ (Low Emission Zone) in the city center.Systems2016-01-1841Article10.3390/systems401000552079-89542016-01-18doi: 10.3390/systems4010005Pierre FossetArnaud BanosElise BeckSonia ChardonnelChristophe LangNicolas MarilleauArnaud PiombiniThomas LeysensAlexis ConesaIsabelle Andre-PoyaudThomas Thevenin<![CDATA[Electronics, Vol. 5, Pages 5: Hardware Activation by Means of PUFs and Elliptic Curve Cryptography in Field-Programmable Devices]]>
http://www.mdpi.com/2079-9292/5/1/5
Reusable design using IP cores requires of efficient methods for protecting the Intellectual Property of the designer and the corresponding license agreements. In this work, a new protection procedure establishing an activation protocol in a similar way to the activation process in the software world is presented. The procedure, named SEHAS (Secure Hardware Activation System) allows the distribution of cores in either Blocked (not functioning) or Demo (functioning with limited features) modes, while ensuring the license agreements by identifying not only the IP core but also the implementation device, using Physically Unclonable Functions (PUF). Moreover, SEHAS secures the exchange of information between the core and the core vendor using an Elliptic Curve Cryptosystem (ECC). This secure channel allows the IP core vendor to send a unique Activation Code to the core in order to switch it to the Activated Mode, thus enabling all its features.Electronics2016-01-1851Article10.3390/electronics501000552079-92922016-01-18doi: 10.3390/electronics5010005Luis ParrillaEncarnación CastilloDiego MoralesAntonio García<![CDATA[Electronics, Vol. 5, Pages 4: Acoustic Wake-Up Receivers for Home Automation Control Applications]]>
http://www.mdpi.com/2079-9292/5/1/4
Automated home applications are to ease the use of technology and devices around the house. Most of the electronic devices, like shutters or entertainment products (Hifi, TV and even WiFi), are constantly in a standby mode, where they consume a considerable amount of energy. The standby mode is necessary to react to commands triggered by the user, but the time the device spends in a standby mode is considered long. In our work, we present a receiver that is attached to home appliances that allows the devices to be activated while they are completely turned off in order to reduce the energy consumed in the standby mode. The receiver contains a low power wake-up module that reacts to an addressable acoustic 20-kHz sound signal that controls home devices that are connected to it. The acoustic wake-up signal can be sent by any kind of speaker that is available in commercial smartphones. The smartphones will operate as transmitters to the signals. Our wake-up receiver consists of two parts: a low power passive circuit connected to a wake-up chip microcontroller and an active micro-electromechanical system (MEMS) microphone that receives the acoustic signal. A duty cycle is required to reduce the power consumption of the receiver, because the signal reception occurs when the microphone is active. The current consumption was measured to be 15 μA in sleep mode and 140 μA in active mode. An average wake-up range of 10 m using a smartphone as a sender was achieved.Electronics2016-01-1551Article10.3390/electronics501000442079-92922016-01-15doi: 10.3390/electronics5010004Amir BannouraFabian HöflingerOmar GorgiesGerd GammJoan AlbesaLeonhard Reindl<![CDATA[Systems, Vol. 4, Pages 4: Modeling Dynamic Decision-Making of Virtual Humans]]>
http://www.mdpi.com/2079-8954/4/1/4
Imagine a person visiting an urban event. At each moment in time, the person has to weigh up different possible actions and make consecutive decisions. For instance, a person might be hungry or thirsty and would therefore like to go somewhere to eat or to drink, or a person might need to go to the toilet and thus go searching for the restrooms. Other possible desires might be to go dancing or to have a rest due to exhaustion. All these examples can be seen in the context of dynamic decision-making. To be able to implement the dynamic decision-making of virtual humans living their lives in a persistent microworld, an advanced concept to solve this—in artificial intelligence research commonly called action selection problem—is required. This article focuses on an novel approach to model the activation of motivations—as an attempt to answer the recurring question of the virtual humans “What to do next?”. The novelty is to use System Dynamics, in general defined as a top-down simulation approach, from the bottom-up inside each instance of the agent population and to implement an action selection mechanism on the basis of this methodology. This approach enables us to model the dynamic decision-making of the virtual humans with stocks and flows resulting in nonlinear motivation evolution. A case study in the context of an urban event documents the application of this innovative method.Systems2016-01-1541Article10.3390/systems401000442079-89542016-01-15doi: 10.3390/systems4010004Oliver Handel<![CDATA[Symmetry, Vol. 8, Pages 4: Synthesis of Chiral Cyclic Carbonates via Kinetic Resolution of Racemic Epoxides and Carbon Dioxide]]>
http://www.mdpi.com/2073-8994/8/1/4
The catalytic synthesis of cyclic carbonates using carbon dioxide as a C1-building block is a highly active area of research. Here, we review the catalytic production of enantiomerically enriched cyclic carbonates via kinetic resolution of racemic epoxides catalysed by metal-containing catalyst systems.Symmetry2016-01-1481Review10.3390/sym801000442073-89942016-01-14doi: 10.3390/sym8010004Xiao WuJosé Castro-OsmaMichael North<![CDATA[Robotics, Vol. 5, Pages 1: HBS-1: A Modular Child-Size 3D Printed Humanoid]]>
http://www.mdpi.com/2218-6581/5/1/1
An affordable, highly articulated, child-size humanoid robot could potentially be used for various purposes, widening the design space of humanoids for further study. Several findings indicated that normal children and children with autism interact well with humanoids. This paper presents a child-sized humanoid robot (HBS-1) intended primarily for children’s education and rehabilitation. The design approach is based on the design for manufacturing (DFM) and the design for assembly (DFA) philosophies to realize the robot fully using additive manufacturing. Most parts of the robot are fabricated with acrylonitrile butadiene styrene (ABS) using rapid prototyping technology. Servomotors and shape memory alloy actuators are used as actuating mechanisms. The mechanical design, analysis and characterization of the robot are presented in both theoretical and experimental frameworks.Robotics2016-01-1351Article10.3390/robotics501000112218-65812016-01-13doi: 10.3390/robotics5010001Lianjun WuMiles LarkinAkshay PotnuruYonas Tadesse<![CDATA[Robotics, Vol. 5, Pages 2: Coordination of Multiple Biomimetic Autonomous Underwater Vehicles Using Strategies Based on the Schooling Behaviour of Fish]]>
http://www.mdpi.com/2218-6581/5/1/2
Biomimetic Autonomous Underwater Vehicles (BAUVs) are Autonomous Underwater Vehicles (AUVs) that employ similar propulsion and steering principles as real fish. While the real life applicability of these vehicles has yet to be fully investigated, laboratory investigations have demonstrated that at low speeds, the propulsive mechanism of these vehicles is more efficient when compared with propeller based AUVs. Furthermore, these vehicles have also demonstrated superior manoeuvrability characteristics when compared with conventional AUVs and Underwater Glider Systems (UGSs). Further performance benefits can be achieved through coordination of multiple BAUVs swimming in formation. In this study, the coordination strategy is based on the schooling behaviour of fish, which is a decentralized approach that allows multiple AUVs to be self-organizing. Such a strategy can be effectively utilized for large spatiotemporal data collection for oceanic monitoring and surveillance purposes. A validated mathematical model of the BAUV developed at the University of Glasgow, RoboSalmon, is used to represent the agents within a school formation. The performance of the coordination algorithm is assessed through simulation where system identification techniques are employed to improve simulation run time while ensuring accuracy is maintained. The simulation results demonstrate the effectiveness of implementing coordination algorithms based on the behavioural mechanisms of fish to allow a group of BAUVs to be considered self-organizing.Robotics2016-01-1351Article10.3390/robotics501000222218-65812016-01-13doi: 10.3390/robotics5010002Jonathan McColganEuan McGookin<![CDATA[Symmetry, Vol. 8, Pages 3: Organocatalytic Asymmetric α-Chlorination of 1,3-Dicarbonyl Compounds Catalyzed by 2-Aminobenzimidazole Derivatives]]>
http://www.mdpi.com/2073-8994/8/1/3
Bifunctional chiral 2-aminobenzimidazole derivatives 1 and 2 catalyze the enantioselective stereodivergent α-chlorination of β-ketoesters and 1,3-diketone derivatives with up to 50% ee using N-chlorosuccinimide (NCS) or 2,3,4,4,5,6-hexachloro-2,5-cyclohexadien-1-one as electrophilic chlorine sources.Symmetry2016-01-1381Article10.3390/sym801000332073-89942016-01-13doi: 10.3390/sym8010003Daniel SánchezAlejandro BaezaDiego Alonso<![CDATA[Axioms, Vol. 5, Pages 2: Non-Abelian Pseudocompact Groups]]>
http://www.mdpi.com/2075-1680/5/1/2
Here are three recently-established theorems from the literature. (A) (2006) Every non-metrizable compact abelian group K has 2|K| -many proper dense pseudocompact subgroups. (B) (2003) Every non-metrizable compact abelian group K admits 22|K| -many strictly finer pseudocompact topological group refinements. (C) (2007) Every non-metrizable pseudocompact abelian group has a proper dense pseudocompact subgroup and a strictly finer pseudocompact topological group refinement. (Theorems (A), (B) and (C) become false if the non-metrizable hypothesis is omitted.) With a detailed view toward the relevant literature, the present authors ask: What happens to (A), (B), (C) and to similar known facts about pseudocompact abelian groups if the abelian hypothesis is omitted? Are the resulting statements true, false, true under certain natural additional hypotheses, etc.? Several new results responding in part to these questions are given, and several specific additional questions are posed.Axioms2016-01-1251Article10.3390/axioms501000222075-16802016-01-12doi: 10.3390/axioms5010002W. ComfortDieter Remus<![CDATA[Econometrics, Vol. 4, Pages 4: A Conditional Approach to Panel Data Models with Common Shocks]]>
http://www.mdpi.com/2225-1146/4/1/4
This paper studies the effects of common shocks on the OLS estimators of the slopes’ parameters in linear panel data models. The shocks are assumed to affect both the errors and some of the explanatory variables. In contrast to existing approaches, which rely on using results on martingale difference sequences, our method relies on conditional strong laws of large numbers and conditional central limit theorems for conditionally-heterogeneous random variables.Econometrics2016-01-1241Article10.3390/econometrics401000442225-11462016-01-12doi: 10.3390/econometrics4010004Giovanni ForchiniBin Peng<![CDATA[IJGI, Vol. 5, Pages 4: An Extended Semi-Supervised Regression Approach with Co-Training and Geographical Weighted Regression: A Case Study of Housing Prices in Beijing]]>
http://www.mdpi.com/2220-9964/5/1/4
This paper proposes an extended semi-supervised regression approach to enhance the prediction accuracy of housing prices within the geographical information science field. The method, referred to as co-training geographical weighted regression (COGWR), aims to fully utilize the positive aspects of both the geographical weighted regression (GWR) method and the semi-supervised learning paradigm. Housing prices in Beijing are assessed to validate the feasibility of the proposed model. The COGWR model demonstrated a better goodness-of-fit than the GWR when housing price data were limited because a COGWR is able to effectively absorb no-price data with explanatory variables into its learning by considering spatial variations and nonstationarity that may introduce significant biases into housing prices. This result demonstrates that a semisupervised geographic weighted regression may be effectively used to predict housing prices.ISPRS International Journal of Geo-Information2016-01-1251Article10.3390/ijgi501000442220-99642016-01-12doi: 10.3390/ijgi5010004Yi YangJiping LiuShenghua XuYangyang Zhao<![CDATA[Electronics, Vol. 5, Pages 3: Simulation of 50-nm Gate Graphene Nanoribbon Transistors]]>
http://www.mdpi.com/2079-9292/5/1/3
An approach to simulate the steady-state and small-signal behavior of GNR MOSFETs (graphene nanoribbon metal-semiconductor-oxide field-effect transistor) is presented. GNR material parameters and a method to account for the density of states of one-dimensional systems like GNRs are implemented in a commercial device simulator. This modified tool is used to calculate the current-voltage characteristics as well the cutoff frequency fT and the maximum frequency of oscillation fmax of GNR MOSFETs. Exemplarily, we consider 50-nm gate GNR MOSFETs with N = 7 armchair GNR channels and examine two transistor configurations. The first configuration is a simplified MOSFET structure with a single GNR channel as usually studied by other groups. Furthermore, and for the first time in the literature, we study in detail a transistor structure with multiple parallel GNR channels and interribbon gates. It is shown that the calculated fT of GNR MOSFETs is significantly lower than that of GFETs (FET with gapless large-area graphene channel) with comparable gate length due to the mobility degradation in GNRs. On the other hand, GNR MOSFETs show much higher fmax compared to experimental GFETs due the semiconducting nature of the GNR channels and the resulting better saturation of the drain current. Finally, it is shown that the gate control in FETs with multiple parallel GNR channels is improved while the cutoff frequency is degraded compared to single-channel GNR MOSFETs due to parasitic capacitances of the interribbon gates.Electronics2016-01-1251Article10.3390/electronics501000332079-92922016-01-12doi: 10.3390/electronics5010003Cedric Nanmeni BondjaZhansong GengRalf GranznerJörg PezoldtFrank Schwierz<![CDATA[Econometrics, Vol. 4, Pages 3: Forecasting Value-at-Risk under Different Distributional Assumptions]]>
http://www.mdpi.com/2225-1146/4/1/3
Financial asset returns are known to be conditionally heteroskedastic and generally non-normally distributed, fat-tailed and often skewed. These features must be taken into account to produce accurate forecasts of Value-at-Risk (VaR). We provide a comprehensive look at the problem by considering the impact that different distributional assumptions have on the accuracy of both univariate and multivariate GARCH models in out-of-sample VaR prediction. The set of analyzed distributions comprises the normal, Student, Multivariate Exponential Power and their corresponding skewed counterparts. The accuracy of the VaR forecasts is assessed by implementing standard statistical backtesting procedures used to rank the different specifications. The results show the importance of allowing for heavy-tails and skewness in the distributional assumption with the skew-Student outperforming the others across all tests and confidence levels.Econometrics2016-01-1141Article10.3390/econometrics401000332225-11462016-01-11doi: 10.3390/econometrics4010003Manuela BraioneNicolas Scholtes<![CDATA[Algorithms, Vol. 9, Pages 8: A Greedy Algorithm for Neighborhood Overlap-Based Community Detection]]>
http://www.mdpi.com/1999-4893/9/1/8
The neighborhood overlap (NOVER) of an edge u-v is defined as the ratio of the number of nodes who are neighbors for both u and v to that of the number of nodes who are neighbors of at least u or v. In this paper, we hypothesize that an edge u-v with a lower NOVER score bridges two or more sets of vertices, with very few edges (other than u-v) connecting vertices from one set to another set. Accordingly, we propose a greedy algorithm of iteratively removing the edges of a network in the increasing order of their neighborhood overlap and calculating the modularity score of the resulting network component(s) after the removal of each edge. The network component(s) that have the largest cumulative modularity score are identified as the different communities of the network. We evaluate the performance of the proposed NOVER-based community detection algorithm on nine real-world network graphs and compare the performance against the multi-level aggregation-based Louvain algorithm, as well as the original and time-efficient versions of the edge betweenness-based Girvan-Newman (GN) community detection algorithm.Algorithms2016-01-1191Article10.3390/a901000881999-48932016-01-11doi: 10.3390/a9010008Natarajan Meghanathan<![CDATA[Algorithms, Vol. 9, Pages 7: An Effective and Efficient MapReduce Algorithm for Computing BFS-Based Traversals of Large-Scale RDF Graphs]]>
http://www.mdpi.com/1999-4893/9/1/7
Nowadays, a leading instance of big data is represented by Web data that lead to the definition of so-called big Web data. Indeed, extending beyond to a large number of critical applications (e.g., Web advertisement), these data expose several characteristics that clearly adhere to the well-known 3V properties (i.e., volume, velocity, variety). Resource Description Framework (RDF) is a significant formalism and language for the so-called Semantic Web, due to the fact that a very wide family of Web entities can be naturally modeled in a graph-shaped manner. In this context, RDF graphs play a first-class role, because they are widely used in the context of modern Web applications and systems, including the emerging context of social networks. When RDF graphs are defined on top of big (Web) data, they lead to the so-called large-scale RDF graphs, which reasonably populate the next-generation Semantic Web. In order to process such kind of big data, MapReduce, an open source computational framework specifically tailored to big data processing, has emerged during the last years as the reference implementation for this critical setting. In line with this trend, in this paper, we present an approach for efficiently implementing traversals of large-scale RDF graphs over MapReduce that is based on the Breadth First Search (BFS) strategy for visiting (RDF) graphs to be decomposed and processed according to the MapReduce framework. We demonstrate how such implementation speeds-up the analysis of RDF graphs with respect to competitor approaches. Experimental results clearly support our contributions.Algorithms2016-01-1191Article10.3390/a901000771999-48932016-01-11doi: 10.3390/a9010007Alfredo CuzzocreaMirel CosulschiRoberto de Virgilio<![CDATA[Computers, Vol. 5, Pages 1: Exponentiated Gradient Exploration for Active Learning]]>
http://www.mdpi.com/2073-431X/5/1/1
Active learning strategies respond to the costly labeling task in a supervised classification by selecting the most useful unlabeled examples in training a predictive model. Many conventional active learning algorithms focus on refining the decision boundary, rather than exploring new regions that can be more informative. In this setting, we propose a sequential algorithm named exponentiated gradient (EG)-active that can improve any active learning algorithm by an optimal random exploration. Experimental results show a statistically-significant and appreciable improvement in the performance of our new approach over the existing active feedback methods.Computers2016-01-0851Letter10.3390/computers501000112073-431X2016-01-08doi: 10.3390/computers5010001Djallel Bouneffouf<![CDATA[Symmetry, Vol. 8, Pages 2: Natural Abundance Isotopic Chirality in the Reagents of the Soai Reaction]]>
http://www.mdpi.com/2073-8994/8/1/2
Isotopic chirality influences sensitively the enantiomeric outcome of the Soai asymmetric autocatalysis. Therefore magnitude and eventual effects of isotopic chirality caused by natural abundance isotopic substitution (H, C, O, Zn) in the reagents of the Soai reaction were analyzed by combinatorics and probability calculations. Expectable enantiomeric excesses were calculated by the Pars–Mills equation. It has been found that the chiral isotopic species formed by substitution in the otherwise achiral reagents provide enantiomeric excess (e.e.) levels that are higher than the sensitivity threshold of the Soai autocatalysis towards chiral induction. Consequently, possible chiral induction exerted by these e.e. values should be taken into account in considerations regarding the molecular events and the mechanism of the chiral induction in the Soai reaction.Symmetry2016-01-0881Article10.3390/sym801000222073-89942016-01-08doi: 10.3390/sym8010002Béla BarabásRóbert KurdiGyula Pályi<![CDATA[Systems, Vol. 4, Pages 3: An Approach for Analyzing the Vulnerability of Small Family Businesses]]>
http://www.mdpi.com/2079-8954/4/1/3
In a given operating environment, small family businesses typically have fewer resources to minimize vulnerability. Identifying this exposure is basic to strategic analysis and, potentially, public policy analysis. This can become even more important when structural change in the environment is expected while its exact character is not known. The implications of climate change for Australian family farms are an example. This paper reports a study designed to analyse the vulnerability of dairy farms in Victoria, Australia. The study draws on production control (applied general systems) theory, value chains and image theory to capture comprehensively the lock-in arising from salient past decisions and impact on the current business structure and strategy. This is the path dependence that defines the constraints and associated options available to small family businesses. The authors identify benefits associated with the use of dynamic analysis of vulnerability over static analysis. Generalizable implications regarding analysis of vulnerability in small family businesses are offered.Systems2016-01-0841Article10.3390/systems401000332079-89542016-01-08doi: 10.3390/systems4010003Lisa CowanVic Wright<![CDATA[IJGI, Vol. 5, Pages 3: Visual-LiDAR Odometry Aided by Reduced IMU]]>
http://www.mdpi.com/2220-9964/5/1/3
This paper proposes a method for combining stereo visual odometry, Light Detection And Ranging (LiDAR) odometry and reduced Inertial Measurement Unit (IMU) including two horizontal accelerometers and one vertical gyro. The proposed method starts with stereo visual odometry to estimate six Degree of Freedom (DoF) ego motion to register the point clouds from previous epoch to the current epoch. Then, Generalized Iterative Closest Point (GICP) algorithm refines the motion estimation. Afterwards, forward velocity and Azimuth obtained by visual-LiDAR odometer are integrated with reduced IMU outputs in an Extended Kalman Filter (EKF) to provide final navigation solution. In this paper, datasets from KITTI (Karlsruhe Institute of Technology and Toyota technological Institute) were used to compare stereo visual odometry, integrated stereo visual odometry and reduced IMU, stereo visual-LiDAR odometry and integrated stereo visual-LiDAR odometry and reduced IMU. Integrated stereo visual-LiDAR odometry and reduced IMU outperforms other methods in urban areas with buildings around. Moreover, this method outperforms simulated Reduced Inertial Sensor System (RISS), which uses simulated wheel odometer and reduced IMU. KITTI datasets do not include wheel odometry data. Integrated RTK (Real Time Kinematic) GPS (Global Positioning System) and IMU was replaced by wheel odometer to simulate the response of RISS method. Visual Odometry (VO)-LiDAR is not only more accurate than wheel odometer, but it also provides azimuth aiding to vertical gyro resulting in a more reliable and accurate system. To develop low-cost systems, it would be a good option to use two cameras plus reduced IMU. The cost of such a system will be reduced than using full tactical MEMS (Micro-Electro-Mechanical Sensor) based IMUs because two cameras are cheaper than full tactical MEMS based IMUs. The results indicate that integrated stereo visual-LiDAR odometry and reduced IMU can achieve accuracy at the level of state of art.ISPRS International Journal of Geo-Information2016-01-0751Article10.3390/ijgi501000332220-99642016-01-07doi: 10.3390/ijgi5010003Yashar Balazadegan SarvroodSiavash HosseinyalamdaryYang Gao<![CDATA[Electronics, Vol. 5, Pages 2: Self-Aligned Metal Electrodes in Fully Roll-to-Roll Processed Organic Transistors]]>
http://www.mdpi.com/2079-9292/5/1/2
We demonstrate the production of organic bottom gate transistors with self-aligned electrodes, using only continuous roll-to-roll (R2R) techniques. The self-alignment allows accurate &lt;5 µm layer-to-layer registration, which is usually a challenge in high-speed R2R environments as the standard registration methods are limited to the millimeter range—or, at best, to tens of µm if online cameras and automatic web control are utilized. The improved registration enables minimizing the overlap between the source/drain electrodes and the gate electrode, which is essential for minimizing the parasitic capacitance. The complete process is a combination of several techniques, including evaporation, reverse gravure, flexography, lift-off, UV exposure and development methods—all transferred to a continuous R2R pilot line. Altogether, approximately 80 meters of devices consisting of thousands of transistors were manufactured in a roll-to-roll fashion. Finally, a cost analysis is presented in order to ascertain the main costs and to predict whether the process would be feasible for the industrial production of organic transistors.Electronics2016-01-0751Article10.3390/electronics501000222079-92922016-01-07doi: 10.3390/electronics5010002Marja VilkmanTeemu RuotsalainenKimmo SolehmainenElina JanssonJohanna Hiitola-Keinänen<![CDATA[IJGI, Vol. 5, Pages 2: Remote Sensing and GIS Applied to the Landscape for the Environmental Restoration of Urbanizations by Means of 3D Virtual Reconstruction and Visualization (Salamanca, Spain)]]>
http://www.mdpi.com/2220-9964/5/1/2
The key focus of this paper is to establish a procedure that combines the use of Geographical Information Systems (GIS) and remote sensing in order to achieve simulation and modeling of the landscape impact caused by construction. The procedure should be easily and inexpensively developed. With the aid of 3D virtual reconstruction and visualization, this paper proposes that the technologies of remote sensing and GIS can be applied to the landscape for post-urbanization environmental restoration. The goal is to create a rural zone in an urban development sector that integrates the residential areas and local infrastructure into the surrounding natural environment in order to measure the changes to the preliminary urban design. The units of the landscape are determined by means of two cartographic methods: (1) indirect, using the components of the landscape; and (2) direct methods, using the landscape’s elements. The visual basins are calculated for the most transited by the population points, while establishing the zones that present major impacts for the urbanization of their landscape. Based on this, the different construction types are distributed (one-family houses, blocks of houses, etc.), selecting the types of plant masses either with ornamentals or integration depending on the zone; integrating water channels, creating a water channel in recirculation and green spaces and leisure time facilities. The techniques of remote sensing and GIS allow for the visualization and modeling of the urbanization in 3D, simulating the virtual reality of the infrastructure as well as the actions that need to be taken for restoration, thereby providing at a low cost an understanding of landscape integration before it takes place.ISPRS International Journal of Geo-Information2016-01-0651Article10.3390/ijgi501000222220-99642016-01-06doi: 10.3390/ijgi5010002Antonio Martínez-GrañaVirginia Valdés Rodríguez<![CDATA[IJFS, Vol. 4, Pages 1: Calisthenics with Words: The Effect of Readability and Investor Sophistication on Investors’ Performance Judgment]]>
http://www.mdpi.com/2227-7072/4/1/1
Since the 1990s, the SEC has advocated for financial disclosures to be in “plain English” so that they would be more readable and informative. Past research has shown that high readability is related to more extreme investor judgments of firm performance. Processing fluency is the prevalent theory to explain this: higher readability increases the investor’s subconscious reliance on the disclosure, so positive (negative) news leads to more positive (negative) judgments. The relationship may not be so simple, though: drawing on research from cognitive psychology, I predict and find that investor financial literacy simultaneously influences investor decision-making, and that it has an interactive effect with readability. When presented with financial disclosure containing conflicting financial information, investors with higher financial literacy make more negative judgments than investors with low financial literacy when the disclosure is easy to read, but the effect becomes insignificant when the disclosure becomes difficult to read. This effect is moderated by a comprehension gap between the two investor groups. Financial literacy and readability interact to impact both how and how well the investor processes financial information.International Journal of Financial Studies2016-01-0541Article10.3390/ijfs401000112227-70722016-01-05doi: 10.3390/ijfs4010001Xiao Cui<![CDATA[Algorithms, Vol. 9, Pages 6: Efficient Metaheuristics for the Mixed Team Orienteering Problem with Time Windows]]>
http://www.mdpi.com/1999-4893/9/1/6
Given a graph whose nodes and edges are associated with a profit, a visiting (or traversing) time and an admittance time window, the Mixed Team Orienteering Problem with Time Windows (MTOPTW) seeks for a specific number of walks spanning a subset of nodes and edges of the graph so as to maximize the overall collected profit. The visit of the included nodes and edges should take place within their respective time window and the overall duration of each walk should be below a certain threshold. In this paper we introduce the MTOPTW, which can be used for modeling a realistic variant of the Tourist Trip Design Problem where the objective is the derivation of near-optimal multiple-day itineraries for tourists visiting a destination which features several points of interest (POIs) and scenic routes. Since the MTOPTW is a NP-hard problem, we propose the first metaheuristic approaches to tackle it. The effectiveness of our algorithms is validated through a number of experiments on POI and scenic route sets compiled from the city of Athens (Greece).Algorithms2016-01-0591Article10.3390/a901000661999-48932016-01-05doi: 10.3390/a9010006Damianos GavalasCharalampos KonstantopoulosKonstantinos MastakasGrammati PantziouNikolaos Vathis<![CDATA[IJGI, Vol. 5, Pages 1: What is an Appropriate Temporal Sampling Rate to Record Floating Car Data with a GPS?]]>
http://www.mdpi.com/2220-9964/5/1/1
Floating car data (FCD) recorded with the Global Positioning System (GPS) are an important data source for traffic research. However, FCD are subject to error, which can relate either to the accuracy of the recordings (measurement error) or to the temporal rate at which the data are sampled (interpolation error). Both errors affect movement parameters derived from the FCD, such as speed or direction, and consequently influence conclusions drawn about the movement. In this paper we combined recent findings about the autocorrelation of GPS measurement error and well-established findings from random walk theory to analyse a set of real-world FCD. First, we showed that the measurement error in the FCD was affected by positive autocorrelation. We explained why this is a quality measure of the data. Second, we evaluated four metrics to assess the influence of interpolation error. We found that interpolation error strongly affects the correct interpretation of the car’s dynamics (speed, direction), whereas its impact on the path (travelled distance, spatial location) was moderate. Based on these results we gave recommendations for recording of FCD using the GPS. Our recommendations only concern time-based sampling, change-based, location-based or event-based sampling are not discussed. The sampling approach minimizes the effects of error on movement parameters while avoiding the collection of redundant information. This is crucial for obtaining reliable results from FCD.ISPRS International Journal of Geo-Information2016-01-0451Article10.3390/ijgi501000112220-99642016-01-04doi: 10.3390/ijgi5010001Peter RanacherRichard BrunauerStefan van der SpekSiegfried Reich<![CDATA[Mathematics, Vol. 4, Pages 2: Barrier Option Under Lévy Model : A PIDE and Mellin Transform Approach]]>
http://www.mdpi.com/2227-7390/4/1/2
We propose a stochastic model to develop a partial integro-differential equation (PIDE) for pricing and pricing expression for fixed type single Barrier options based on the Itô-Lévy calculus with the help of Mellin transform. The stock price is driven by a class of infinite activity Lévy processes leading to the market inherently incomplete, and dynamic hedging is no longer risk free. We first develop a PIDE for fixed type Barrier options, and apply the Mellin transform to derive a pricing expression. Our main contribution is to develop a PIDE with its closed form pricing expression for the contract. The procedure is easy to implement for all class of Lévy processes numerically. Finally, the algorithm for computing numerically is presented with results for a set of Lévy processes.Mathematics2016-01-0441Article10.3390/math401000222227-73902016-01-04doi: 10.3390/math4010002Sudip ChandraDiganta Mukherjee<![CDATA[Technologies, Vol. 4, Pages 2: Fate and Transport of Fire-Born Particles in Porous Media]]>
http://www.mdpi.com/2227-7080/4/1/2
A variety of hazardous substances may be generated from the burning materials during fire extinguishing operations, depending on the location, type, and place of the fire. As a result, the fire-extinguishing water may act as a carrier for these nano- and micro-sized fire-born particles, including various types of associated contaminants, and may cause contamination of soil and groundwater resources. While airborne particles from fires have been studied, it is currently not well known what types of nano- and micro-sized contaminants are typically carried by the fire-extinguishing water and how these contaminants can be transported in the natural environment. The main purpose of this study was to increase the understanding about the occurrence and physical and chemical properties of nanoparticles commonly found in discharge water from fire extinguishing operations. The current study was based on collection of original samples from a fire location. A detailed characterization of the particles present in the extinguishing water was performed including both quantification of contaminants associated with the particles (such as metals and polycyclic aromatic hydrocarbons (PAHs) as well as measurement of properties related to the mobility of these particles through porous media. Such mobility properties include size distributions of the particles and the porous media, surface charges and solution chemistry). Results indicate that metals and PAHs are present in both finer and relatively larger fire-born particles. The particles larger than 11 μm were not mobile in porous media. The mobility of the finer particles (&lt;11 μm) was generally high but was dependent on the solution chemistry. Low mobility of large particles in porous media indicates that a large amount of the contamination can likely be trapped in the top soil layer even though the fire extinguishing water infiltrates.Technologies2015-12-3141Article10.3390/technologies401000222227-70802015-12-31doi: 10.3390/technologies4010002Prabhakar SharmaFritjof FagerlundUlrika IverfeldtAmanda Eskebaek<![CDATA[Algorithms, Vol. 9, Pages 5: A Family of Iterative Methods for Solving Systems of Nonlinear Equations Having Unknown Multiplicity]]>
http://www.mdpi.com/1999-4893/9/1/5
The singularity of Jacobian happens when we are looking for a root, with multiplicity greater than one, of a system of nonlinear equations. The purpose of this article is two-fold. Firstly, we will present a modification of an existing method that computes roots with known multiplicities. Secondly, will propose the generalization of a family of methods for solving nonlinear equations with unknown multiplicities, to the system of nonlinear equations. The inclusion of a nonzero multi-variable auxiliary function is the key idea. Different choices of the auxiliary function give different families of the iterative method to find roots with unknown multiplicities. Few illustrative numerical experiments and a critical discussion end the paper.Algorithms2015-12-3191Article10.3390/a901000551999-48932015-12-31doi: 10.3390/a9010005Fayyaz AhmadS. Serra-CapizzanoMalik UllahA. Al-Fhaid<![CDATA[Axioms, Vol. 5, Pages 1: On some Integral Representations of Certain G-Functions]]>
http://www.mdpi.com/2075-1680/5/1/1
This is a brief exposition of some statistical techniques utilized to obtain several useful integral equations involving G-functions.Axioms2015-12-3151Article10.3390/axioms501000112075-16802015-12-31doi: 10.3390/axioms5010001Seemon Thomas<![CDATA[JRFM, Vol. 9, Pages 1: The Two Defaults Scenario for Stressing Credit Portfolio Loss Distributions]]>
http://www.mdpi.com/1911-8074/9/1/1
The impact of a stress scenario of default events on the loss distribution of a credit portfolio can be assessed by determining the loss distribution conditional on these events. While it is conceptually easy to estimate loss distributions conditional on default events by means of Monte Carlo simulation, it becomes impractical for two or more simultaneous defaults as then the conditioning event is extremely rare. We provide an analytical approach to the calculation of the conditional loss distribution for the CreditRisk + portfolio model with independent random loss given default distributions. The analytical solution for this case can be used to check the accuracy of an approximation to the conditional loss distribution whereby the unconditional model is run with stressed input probabilities of default (PDs). It turns out that this approximation is unbiased. Numerical examples, however, suggest that the approximation may be seriously inaccurate but that the inaccuracy leads to overestimation of tail losses and, hence, the approach errs on the conservative side.Journal of Risk and Financial Management2015-12-3191Article10.3390/jrfm901000111911-80742015-12-31doi: 10.3390/jrfm9010001Dirk Tasche<![CDATA[Algorithms, Vol. 9, Pages 4: A Novel Complex-Valued Encoding Grey Wolf Optimization Algorithm]]>
http://www.mdpi.com/1999-4893/9/1/4
Grey wolf optimization (GWO) is one of the recently proposed heuristic algorithms imitating the leadership hierarchy and hunting mechanism of grey wolves in nature. The aim of these algorithms is to perform global optimization. This paper presents a modified GWO algorithm based on complex-valued encoding; namely the complex-valued encoding grey wolf optimization (CGWO). We use CGWO to test 16 unconstrained benchmark functions with seven different scales and infinite impulse response (IIR) model identification. Compared to the real-valued GWO algorithm and other optimization algorithms; the CGWO performs significantly better in terms of accuracy; robustness; and convergence speed.Algorithms2015-12-3091Article10.3390/a901000441999-48932015-12-30doi: 10.3390/a9010004Qifang LuoSen ZhangZhiming LiYongquan Zhou